The Effects of Drugs on Driving

This module introduces the different types of drugs that can impair driving. It also provides an overview of the different research methods that are typically used to measure drug-impaired driving in laboratories as well as the real world, and general limitations associated with these methods are briefly discussed.

The research about the impairing effects of drugs on the human body (i.e., physiological) and their effects on driving (i.e., functional skills required for vehicle operation) are discussed according to the seven different categories of drugs. In addition, the frequency of detection of these drugs in drivers, and the effects of these drugs when combined with alcohol, sleep deprivation, or other factors are also described in instances when additive effects exist. Information regarding the effects of new psychoactive substances (NPS or “designer drugs”) is provided where possible, although research on these types of drugs is limited.

  1. What functional abilities are necessary for safe driving?
  2. What are the different types of drugs that can impair driving?
  3. How do researchers measure the impairing effects of drugs on driving abilities?
  4. What are the limitations of the current research measuring the effects of drugs on driving ability?

Effects of Specific Drugs on Driving

  1. What is this drug?
  2. What is the frequency of detection of this drug in drivers?
  3. What are the impairing effects of this drug on driving?
  4. How do other factors (alcohol, sleep deprivation) interact with this drug to affect driving ability?

1. What functional abilities are necessary for safe driving?

Driving is a complex self-paced task that requires many skills and abilities to be completed simultaneously, and it requires that information be processed at a rapid pace while utilizing visual (ex: ability to scan the road for hazards), cognitive (ex: ability to divide attention between multiple concurrent events) and motor skills (ex: ability to perform physical movements such as turning the steering wheel, pressing acceleration and brake pedals). The processes drivers use to operate a vehicle can be divided into three steps: perception, decision and reaction. These three steps are assumed to happen consecutively, and depend on the driver’s visual, cognitive and motor abilities. Impairment in any or all of these abilities can lead to unsafe driving.1

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2. What are the different types of drugs that can impair driving?

Drugs that can impair driving are categorized according to the seven drug categories, established by the International Drug Evaluation and Classification Program (DECP). These include: cannabis2, central nervous system (CNS) depressants, central nervous system (CNS) stimulants, hallucinogens, dissociative anesthetics, narcotic analgesics, and inhalants.

There are also New Psychoactive Substances (NPS) that are frequently not included under the international drug control conventions. There are currently over 450 NPS being monitored by the European Union, with over half being reported since 2013.3 An NPS is a synthetic drug that is designed to mimic the pharmacological effects of existing controlled substances. It is unlikely that synthetic drugs are detected using the common standardized drug test.4 An NPS is characterized by the following features: psychoactive properties; a level of potential harm comparable to internationally controlled drugs; and newly available, rather than newly invented.5

2 The term “cannabis” refers to the cannabis plant that contains more than 100 cannabinoids. The primary psychoactive component of cannabis is delta-9-tetrahydrocannabinol, commonly known as THC. THC and its psychoactive metabolite, 11-hydroxy-THC or 11-OH-THC, and primary inactive metabolite, 11-nor-9-carboxy-THC or THC-COOH are frequently measured in biological fluids to document cannabis intake.

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3. How do researchers measure the impairing effects of drugs on driving abilities?

Laboratory tests. Researchers use laboratory tests that measure cognitive or psychomotor abilities thought to be related to or involved in driving. These tests are typically validated and reliable measures to assess specific cognitive capacities and physical motor coordination.

Cognitive tests evaluate the effects of a drug on these specific capacities: attention (simple and divided), perception (auditory, time and visual), memory (long and short-term), vigilance, logical reasoning, problem-solving and decision-making. Examples of validated tests include the Tower of London task, the Wisconsin Card Sorting Task, the Time Wall test, and the Object Movement Estimation under Divided Attention (OMEDA).

Psychomotor tests measure the effects of a drug on participant performance during actions such as body sway, motor coordination and reaction time. Examples of specific tests commonly used to evaluate the effects of drugs include Simple Reaction Time and the Critical Tracking task.6

Simulator tests. Researchers also employ driving simulators to evaluate how the administration of a drug can affect driving. Driving simulators can vary in terms of the level of immersion, which can range from a simple desktop display to a full car cabin with a 360 degree display. Regardless, all simulators display an interactive virtual roadway (i.e., driving scenario) and the participant is directed to perform specific navigational and driving tasks on the virtual roadway via a steering wheel, accelerator and brake pedal. Drivers are administered a specific drug dose or placebo and instructed to complete a driving scenario during which they must perform a variety of actions. Measures typically include: lane weaving behaviours (variability in lateral lane position), speeding behaviours (average speed, speed variability), headway maintenance (the amount of headway distance maintained between the driver’s vehicle and the vehicle in front), braking reaction time, and near-crash and collisions.7

On-road tests. On-road driving tests involve study participants operating a real vehicle, in the presence of a driving instructor who has a secondary set of vehicle controls, either on a closed track or on a public road. Test cars are usually fitted with devices to measure speed, lane positioning, acceleration/ brake use, and video cameras to record the driver’s actions/errors.8

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4. What are the limitations of the current research that measures the effects of drugs on driving ability?

Laboratory tests of cognitive and psychomotor capacities often only measure a single skill or ability related to driving performance, and it is well-known that driving ability engages a combination of cognitive, psychomotor and motor functions.9 Even when a series of tests are used, they are administered independently of each other and many are short and relatively simple, and consequently fail to replicate the complex skills or engage the precise psychomotor and cognitive capacities required for driving.10

Driving simulators also have limitations since they can never fully replicate authentic driving. Participants may be less careful, as they are aware that it is a safe and artificial environment. As a result, driver errors and risk-taking behaviours may be exaggerated.11 Additionally, driving scenarios are often short, involve few elements, engage a limited range of cognitive and psychomotor capacities, and thus do not replicate the complicated conditions that drivers may normally experience.12

The central limitation of on-road driving tests is the safety concern associated with placing drug-impaired drivers on the road, though these can be mitigated by using closed course tests and the presence of driving instructors who can take control of the vehicle when necessary.

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What is cannabis?

Cannabis is the scientific term for the products of the cannabis plants, including marijuana, sinsemilla and hashish. The main psychoactive component is ∆9-tetrahydrocannabinol (THC). Cannabis is the most commonly used illicit drug.13 The short-term effects of cannabis use include increased heart rate, distorted perceptions, impaired short-term memory, impaired coordination, relaxation, and feelings of euphoria. In contrast, some users experience anxiety, paranoia and/or panic attacks.

New psychoactive substances (NPS) that have cannabis-like effects are termed synthetic cannabinoids. The synthetic form is abused recreationally, has many street names including “spice”. Synthetic cannabinoids are the most popular synthetic substances.14

Is cannabis frequently detected in drivers?
Aside from alcohol, cannabis is the most frequently detected drug in fatally injured drivers across North America, Europe and Australia.15 Recently, some studies also examined the prevalence of synthetic cannabinoids in drivers. Although the prevalence of synthetic cannabinoids is not similar to the traditional form of the drug, studies show that synthetic cannabinoids are also found in the general driving population16 as well as fatally injured drivers.17 The latest 2013-2014 National Roadside Survey (NRS) showed that cannabis use in the general United States driving population increased by 48% from the previous 2007 NRS. The authors speculated that this increase may be due to changes in state policies for medical and legal recreational cannabis, although it is not certain whether this is the case without individual state data.18 However, a recent study in Washington State, where cannabis has been legally sold since 2014, showed a significant increase in drivers testing positive for cannabis (11.6% vs. 16.4%) when comparing the percentage from before cannabis was legally sold to after the implementation of this new law.19 In addition to this, Washington State has seen a twofold increase in fatal crashes involving drivers who are THC-positive (8% in 2013 to 17% in 2014).20

Can cannabis impair driving abilities, and if so, how?
Low doses of cannabis produce mild to moderate impairment in cognitive and psychomotor abilities. Studies involving larger doses showed significant impairment in cognitive, psychomotor and driving performance. The driving measures that are impaired include variability in speed maintenance, lane weaving, increased variability in headway, and increased reaction times.21

Cannabis use has been associated with a significantly increased risk of fatal crash involvement, with an odds ratio ranging from 1.8 to 2.8, in other words, drivers that use cannabis are at an increased risk (anywhere from 1.8 to 2.8 times higher odds) of injury.22 Furthermore, the odds of drivers being found responsible for a crash increased with rising cannabis concentrations in the blood.23

Are the effects of cannabis on driving ability impacted by other factors, such as alcohol, or sleep deprivation?
Alcohol has an additive impairing effect when used in combination with cannabis. This means that the ability to compensate for the impairing effects of low doses of THC is negated when alcohol and THC are used together.24 Furthermore, both multiple drug use and sleep deprivation increased the impairing effects of cannabis.

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What are central nervous system (CNS) depressants?

CNS depressants slow down the activity of the central nervous system resulting in sedation, relaxation, and impaired motor coordination.25 Drugs included in the CNS depressant category can be medicinal, legal or illegal. For the purpose of this curriculum, alcohol was excluded from this category. More information about alcohol and its impairing effects can be found at Change the Conversation. Examples of CNS depressants include barbiturates and benzodiazepines, and non-benzodiazepines. The short-term effects of CNS depressants involve sedation that slows body and brain functions, including drowsiness and reduced vigilance, impaired motor coordination and reaction time, and information processing speed. Larger doses can result in confusion, amnesia, and disorientation. There is some evidence that prolonged use can result in the development of partial tolerance to some effects; however, an increased dose can produce impairing effects by overriding the partial tolerance.

There also are NPS with depressant-like effects (such phenazepam, methoxetamine) that are synthetic drugs with effects similar to benzodiazepines.

Which CNS depressants are most frequently detected in drivers?
Anti-depressants and benzodiazepines are the most frequently detected CNS depressants in drivers involved in serious injury or fatal crashes other than alcohol. 26

Can CNS depressants impair driving abilities, and if so, how?
Experimental studies examining the effects of CNS depressants on driving performance have focused on benzodiazepines, anti-anxiety tranquillizers and non-benzodiazepine hypnotics. Results consistently showed impaired information processing, attention, concentration, memory and reaction time following use of benzodiazepine and several non-benzodiazepine hypnotics. These drugs significantly impaired divided attention abilities and increased lane weaving, speed variability.27

Studies show that the use of benzodiazepines and non-benzodiazepine hypnotics is also associated with a moderately elevated crash risk.28 Furthermore, the use of benzodiazepines with driving was associated with 5 times the risk of injury (odds ratio 5.05).29

Are the effects of CNS depressants on driving ability impacted by other factors, such as alcohol, or sleep deprivation?
Alcohol increases the impairing effects of benzodiazepines and non-benzodiazepine hypnotics.30 Sleep deprivation can also exaggerate the impairing effects of a CNS depressant, resulting in greater reduction in concentration and vigilance while driving.31

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What are central nervous system (CNS) stimulants?

CNS stimulants affect the areas of the brain responsible for attention, perception, and other cognitive and motor functions. CNS stimulants accelerate certain vital physiological and mental functions of the body, such as increased heart rate and increased alertness.32

Drugs included under the CNS stimulants category include cocaine, amphetamines, and synthetic cathinones. Cocaine is an illegal drug that is derived from the leaves of the coca plant. It is used recreationally for its euphoric and energizing effects. Amphetamines are prescription medications to treat attention deficit hyperactivity disorder (ADHD) and narcolepsy. In prescription form, amphetamines are usually consumed orally as tablets. The illegal street form of amphetamine is typically known as “speed”, which comes as a white powder that is snorted, smoked or injected. Methamphetamine is a powerful stimulant occasionally used clinically to treat ADHD and narcolepsy, but is more commonly used illegally for recreational purposes or by those suffering from drug use disorders.

The short-term effects of a CNS stimulant include increased heart rate, blood pressure, body temperature, rate of speech, pupillary dilation, euphoria, and alertness, as well as over-confidence, erratic violent behaviour, nervousness and paranoia.

NPS with stimulant-type effects are called synthetic cathinones, which include substances such as mephedrone, methylone and methylenedioxypyrovalerone (MDPV). These substances are also referred to as “bath salts” and have similar physiological effects to stimulants.33

Which CNS stimulants are most frequently detected in drivers?
Cocaine is the CNS stimulant that is most frequently detected in drivers involved in serious injury or fatal crashes. 34

Can CNS stimulants impair driving abilities, and if so, how?
Findings from available experimental research about the effects of CNS stimulants on driving-related capacities generally come from studies that administered low doses, which are not representative of real-world recreational use. Laboratory studies show that amphetamine and methamphetamine in low doses can improve some aspects of cognitive and psychomotor abilities related to driving. However, driving simulator studies found that amphetamines and methamphetamines significantly impair simulated driving abilities by increasing erratic or risky behavior. The self-reported driving behaviours of cocaine users include erratic and risky driving behaviours.35

Drivers using CNS stimulants, such as amphetamines and cocaine, are at double the risk of injury (odds ratio 2.10). Furthermore, stimulant use has been associated with a significantly increased risk of fatal crash involvement, with an odds ratio of 3.57.36

Are the effects of CNS stimulants on driving ability impacted by other factors, such as alcohol, or sleep deprivation?
The combination of cocaine and alcohol produces a more intense high from cocaine and decreases unwanted effects of coming down off a cocaine high.37 The combination of cocaine and alcohol form a new compound called cocaethylene, which lasts longer and has greater impairing effects than either substance alone. It has been suggested that individuals may be more confident to get behind the wheel since some consequences of alcohol intoxication (e.g., sedation) are masked by the effects of cocaine. 38

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What are hallucinogens?

Hallucinogens are drugs that effect ones’ perception by distorting sensory messages sent to the brain.39 Examples of hallucinogens include lysergic acid diethylamide (LSD), peyote, psilocybin and methylenedioxymethamphetamine (MDMA, also known as ecstasy). MDMA is chemically related to both mescaline, which produces hallucinogenic effects, and amphetamines, which results in its frequent categorization as a CNS stimulant. The short-term effects of hallucinogens include increased heart rate and body temperature, dilated pupils, distorted or altered sensory perceptions, and visual or auditory hallucinations. 40

NPS with hallucinogenic-type effects mostly fall under the NBOMes (N-methoxybenzyl) classification, which includes substances that mimic the effects of LSD.41

Which hallucinogens are most frequently detected in drivers?
MDMA (ecstasy) is most frequently detected in fatally injured drivers42. The incidence of other hallucinogens detected in drivers is rare.43

Can hallucinogens impair driving abilities, and if so, how?
Experimental studies found significant impairment in skills directly related to driving, such as the ability to adjust the speed of the vehicle to adapt to the driving environment, and incorrect signalling (not signalling when changing lanes, exiting highways, making turns). Laboratory studies showed that MDMA decreases working memory and movement perception; faculties which are also important for driving. 44

Are the effects of hallucinogens on driving ability impacted by other factors, such as alcohol, or sleep deprivation?
Drivers under the influence of MDMA and alcohol report a lower subjective feeling of alcohol intoxication, but actual performance continues to be affected. Drivers using MDMA and alcohol exhibit increased lane weaving behaviour. Furthermore, MDMA does not compensate for the effects of sleep deprivation, and drivers who took MDMA while sleep deprived exhibited increased lane weaving behaviours.45 Therefore, the use of MDMA with other substances, and the additive effects of sleep deprivation from participation in all night parties or raves, when MDMA and alcohol are often consumed, were shown to negatively impact driving performance.

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What are dissociative anaesthetics?

Dissociative anaesthetics reduce pain by reducing the brain’s perception of pain.46 Common drugs that fall under the dissociative anaesthetics category include phencyclidine (“PCP” “Angel Dust”) and ketamine (“K”, “Special K”). PCP was initially used as a surgical anesthetic, but its clinical use in humans was stopped due to its ability to induce severe delirium and hallucinogenic effects. Ketamine was also initially used clinically as a human anaesthetic. Ketamine is now limited to veterinary use as a large animal tranquilizer and in pediatric surgery. The short-term effects include increased heart rate, blood pressure, sedation, distractibility, time and space distortions, disorientation, decreased awareness, sensitivity to pain, and motor coordination, and amnesia.47

New psychoactive substances such as diphenidine, methoxphenidine, 3-methoxy-phencyclidine (3-meo-pcp) and 4-methoxy-phencyclidine (4-meo-pcp) are derivatives of and drug substitutes for PCP and have effects similar to other dissociative anesthetics.48

Which dissociative anaesthetics are most frequently detected in drivers?
Dissociative anaesthetics are not frequently detected in drivers. According to the Alcohol and Drug Crash Problem Report: 2012 prepared by TIRF for the Canadian Council of Motor Transport Administrators (CCMTA), dissociative anaesthetics were detected in fewer than 2% of fatally injured drivers in Canada. In addition, little data are available regarding the specific detection rates of each type of dissociative anaesthetic among drivers.

Can dissociative anaesthetics impair driving abilities, and if so, how?
Laboratory research indicates that severe cognitive and psychomotor impairments do occur with ketamine intake, including deficits in divided attention and reaction time.49 Other observational studies examined roadside detection of ketamine, finding similar indices of ketamine impairment.50 A review of the existing research concluded that ketamine causes significant impairment in various functional abilities related to driving.51

Are the effects of dissociative anaesthetics on driving ability impacted by other factors, such as alcohol, or sleep deprivation?
Alcohol and some types of CNS depressants can increase the effects of dissociative anaesthetics.52

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What are narcotic analgesics?

Narcotic analgesics are prescribed to treat pain, both acute and chronic, but can also be abused recreationally as an illicit drug.53 Opioids54 are the primary narcotic analgesics in this category, categorized as medicinal or illegal, and natural, semi-synthetic or fully synthetic. Specifically, opiates are naturally derived and include morphine and codeine. Opioids are semi-synthetic or synthetic, but all function like opiates. These include heroin, oxycodone, hydrocodone, oxymorphone, and hydromorphone. The short-term psychological and physiological effects of narcotic analgesics include pain relief, drowsiness, sedation, psychomotor impairment, decreased alertness, decreased pulse, respiratory depression, inability to concentrate, constricted pupils, and euphoria. Individuals on stable medicinal doses of narcotic analgesics will generally develop partial tolerance to the effects of the drug within the first several weeks of use. However, changes in dose or combining the narcotic analgesic with other drugs or alcohol may overcome the partial tolerance.55

Synthetic opioids, such as fentanyl and its’ derivatives, are hundreds of times more potent than heroin. Fentanyl can sometimes be prescribed for chronic pain management, but non-pharmaceutical fentanyl and fentanyl NPS have given rise to a new opioid epidemic.56

Which narcotic analgesics are most frequently detected in drivers?
Roadside survey results show that use of prescription opioids is more prevalent than illicit opioids in the general driving population.57 Although there is currently no established prevalence rate for driving under the influence of non-prescription synthetic opioids such as fentanyl analogs, the high rate of abuse for this substance and its’ derivatives may be reflected in data on impaired driving and fatal crashes.

Can narcotic analgesics impair driving abilities, and if so, how?
Few research studies assess the effects of narcotic analgesics on driving ability, and available studies reported inconsistent results. In general, studies examining first-time users of medicinal opioids showed impairments in driving involving poor vehicle control and increased lane weaving.58 Those who use medicinal opioids over a period of time generally develop a partial tolerance to their impairing effects, and demonstrate less driving impairment.59

Narcotic use was associated with a significantly increased risk of fatal crash involvement, with an odds ratio of 3.03.60 Furthermore, drivers using opiates are at double the risk for injury (odds ratio 2.35).61

Are the effects of narcotic analgesics on driving ability impacted by other factors, such as alcohol, or sleep deprivation?
The partial tolerance built up by those who have taken opioids for a longer period of time can be negatively impacted by consuming alcohol or other drugs. As a result, they may experience the sedating effects similar to when they first used this drug, and in turn demonstrate impairment while driving.62 Although there is evidence that narcotic analgesics have the potential to impair driving, studies showed that controlled use of medicinal narcotics can improve driving abilities by alleviating potentially impairing symptoms of a persons’ underlying condition (e.g., chronic pain).63

54 The term “opioid” is used to refer to all opium-like substances (including opiates and opioids), and for the purposes of this module the term.

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What are inhalants?

Inhalant drugs include a wide range of volatile substances that are taken for their mind-altering effects. Drugs within the inhalants category include nitrates, aerosols, gasoline, toluene, plastic cement, paint, solvent, hairspray and various other gases.64 The short-term effects of inhalants include dizziness, euphoria, reduced ability to concentrate, distorted perceptions of time and distance, and confusion. Large doses result in severe intoxication and can cause tremors, paralysis, unconsciousness, coma and death. Toluene abuse, like other inhalants, can cause brain, liver, and kidney damage, and permanent memory, attention deficits, and death.65

Which inhalants are most frequently detected in drivers?
Inhalants are rarely found in drivers (both in the general driving population and fatally injured drivers) most likely due to their short duration of action.66

Can inhalants impair driving abilities, and if so, how?
A few laboratory studies that administered low doses of volatiles to humans found marked cognitive impairments, including on working memory, higher cognitive functions, inability to concentrate, decreased reaction time, and loss in visual perception.67

Are the effects of inhalants on driving ability impacted by other factors, such as alcohol, or sleep deprivation?
Inhalants and alcohol are potent nervous system depressants, such that they greatly reduce the essential functioning of the central nervous system. When consumed together, there is a greater risk of loss of consciousness and cardiac arrest due to the reduced rate of breathing.68

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Drug-impaired driving can be studied using different research methods, both within laboratories and the real world, although these studies often do not involve large doses of drugs, or combinations of drugs that are typically found in the real world. Findings from each of these types of studies provide a different perspective on the drug-impaired driving problem, and collectively, results of these studies provide important information to increase overall understanding of this issue.

Generally studies indicate that cannabis is the most frequently detected drug (other than alcohol) in fatally injured drivers and show that consumption of this drug can affect driving abilities. Central nervous system depressants such as barbiturates and benzodiazepines, and central nervous system stimulants such as cocaine also are shown to affect skills needed for safe driving, and these drugs are also detected among fatally injured drivers. Other categories of drugs are less often detected in fatally injured drivers, although the hallucinogen MDMA is more prevalent.

Educational campaigns to increase awareness about the impairing effects of illegal as well as prescription drugs are much needed. A focus on cannabis in particular is important in the near-term to dispel beliefs that the use of cannabis while driving does not pose risk.

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  • Movig, K. L., Mathijssen, M. P. M., Nagel, P. H. A., Van Egmond, T., De Gier, J. J., Leufkens, H. G. M., & Egberts, A. C. (2004). Psychoactive substance use and the risk of motor vehicle accidents. Accident Analysis & Prevention, 36(4), 631-636.
  • Patil, V., Tewari, A., & Rao, R. (2016). New psychoactive substances: Issues and challenges. Journal of Mental Health and Human Behaviour, 21(2), 98.
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  • Ramaekers, J. G., Kuypers, K. P., & Samyn, N. (2006). Stimulant effects of 3, 4‐methylenedioxymethamphetamine (MDMA) 75 mg and methylphenidate 20 mg on actual driving during intoxication and withdrawal. Addiction, 101(11), 1614-1621.
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  • 24/7 program: A post-conviction program that grants offenders an unrestricted driving privilege in exchange for daily alcohol and drug testing to measure sobriety. Participants are required to report for alcohol and/or drug testing twice a day at a pre-determined facility, and may also be required to wear a drug patch and/or use a continuous alcohol monitor. Offenders who test positive for alcohol and/or drugs are subject to escalating sanctions.
  • Administrative hearing: A driver may request a hearing to contest an action or sanction against their driving privilege that was imposed by a driver licensing agency on a variety of grounds. The purpose of the hearing is to permit drivers an opportunity to review the evidence and contest the action. Drivers are informed about the legal grounds for the action, and are able to present evidence, witnesses and testimony to support a request to the licensing agency to modify or rescind the action. Hearings are typically recorded and rules applying to hearings are specified by the licensing agency.
  • Aerosols: A substance contained under pressure and able to be released as a fine spray, typically by means of a propellant gas. When used as a recreational drug, aerosols are classified as an inhalant.
  • Alcohol ignition interlock: An alcohol ignition interlock is a breath testing device that connects to the starter or ignition, or other on-board computer system of a vehicle. The device prevents the vehicle from starting if breath test results shows a breath alcohol concentration (BrAC) is found to exceed a certain pre-set limit (usually corresponding to blood alcohol concentration of .02). This device also requires drivers to continue to pass repeated breath tests while the vehicle is in use to ensure that they remain sober. In addition, these programmable devices possess a range of anti-circumvention features.
  • Alcohol-impaired driving: A criminal offence whereby one’s driving ability is impaired due to the consumption of alcohol in excess of a legal threshold. Jurisdictions often utilize a per se limit of .05 to .08mg/%. In addition to a per se limit, many jurisdictions also have an alcohol-impaired driving offence that is based on behavioural indicators of impairment which permits drivers under the per se limit to also be charged with an offence.
  • Amphetamine: Amphetamines are a synthetic, addictive, mood altering drug and are classified as a CNS stimulant drug.
  • Anti-anxiety tranquillizers: A tranquilizer is a drug that acts on the central nervous system and is used to calm, decrease anxiety, or help a person to sleep. Often called depressants because they suppress the central nervous system and slow the body down, they are used to treat mental illness as well as common anxiety and sleeplessness. Anti-anxiety tranquilizers are classified as a CNS depressant.
  • Antidepressants: Drugs used for the treatment of major depressive disorders and other conditions, including dysthymia, anxiety disorders, obsessive compulsive disorder, eating disorders, chronic pain, neuropathic pain and, in some cases, dysmenorrhoea, snoring, migraine, attention-deficit hyperactivity disorder (ADHD), addiction, dependence, and sleep disorders. Antidepressants are classified as a CNS depressant.
  • Attention deficit hyperactivity disorder (ADHD): A mental disorder of the neurodevelopmental type. It is characterized by problems paying attention, excessive activity, or difficulty controlling behavior which is not appropriate for a person’s age.
  • Barbiturates: Drugs that act as central nervous system depressants, and can therefore produce a wide spectrum of effects ranging from mild sedation to total anesthesia.
  • Behavioural impairment laws: This type of laws is based upon behavioural measures of impairment and police officers are required to document observed impaired behaviour that is directly linked to consumption of a specific drug. Evidence that is gathered may include observations by officers while the vehicle in motion, during contact with the driver and throughout the interaction with the driver. Drivers may be required to perform Standardized Field Sobriety Tests (SFSTs) and/or a battery of tests by a trained Drug Recognition Expert (DRE). Suspected impairment is confirmed using toxicological analysis.
  • Benzodiazepines: Benzodiazepines enhance the effect of the neurotransmitter gamma-aminobutyric acid (GABA) at the GABAA receptor, resulting in sedative, hypnotic (sleep-inducing), anxiolytic (anti-anxiety), anticonvulsant, and muscle relaxant properties. High doses of many shorter-acting benzodiazepines may also cause anterograde amnesia and dissociation. These properties make benzodiazepines useful in treating anxiety, insomnia, agitation, seizures, muscle spasms, alcohol withdrawal and as a premedication for medical or dental procedures. Benzodiazepines are categorized as either short-, intermediate-, or long-acting. Short- and intermediate-acting benzodiazepines are preferred for the treatment of insomnia; longer-acting benzodiazepines are recommended for the treatment of anxiety. Benzodiazepines are classified as a CNS depressant.
  • Blood alcohol concentration (BAC): A specific measurement of the level or concentration of alcohol in a person’s blood that is usually measured as mass per volume using the number of grams of alcohol in 100grams of blood. For example, 0.08grams of alcohol in 100 grams of blood is measured as .08.
  • Cannabinoids: Cannabinoids are a group of active compounds found in the cannabis plant. Cannabinoids act on the cannabinoid receptors in cells and alter neurotransmitter release in the brain.
  • Cannabis: The term “cannabis” refers to the cannabis plant that contains more than 100 cannabinoids. The primary psychoactive component of cannabis is delta-9-tetrahydrocannabinol, commonly known as THC. THC and its psychoactive metabolite, 11-hydroxy-THC or 11-OH-THC, and primary inactive metabolite, 11-nor-9-carboxy-THC or THC-COOH are frequently measured in biological fluids to document cannabis intake.
  • Case-control studies: A type of study that compares people with a disease or condition (‘cases’) to another group of people from the same population who do not have that disease or condition (‘controls’). A case-control study is designed to identify risks and trends, and suggest some possible causes for disease, or for particular outcomes.
  • Central nervous system depressant: This type of drug results in the physiological depression of the central nervous system that can result in decreased rate of breathing, decreased heart rate, and loss of consciousness possibly leading to coma or death. CNS depression is specifically the result of inhibited brain activity.
  • Central nervous system stimulant: These types of drugs and medicines speed up physical and mental processes.
  • Cocaethylene: Cocaethylene is the ethyl ester of benzoylecgonine. It is structurally similar to cocaine, which is the methyl ester of benzoylecgonine. Cocaethylene is formed by the liver when cocaine and ethanol coexist in the blood.
  • Cocaine: A crystalline alkaloid obtained from the coca plant that is an illicit drug in many jurisdictions. As an illicit substance, cocaine (also referred to as “coke”), is identified as a clear white powdery substance. It is commonly snorted, inhaled, or injected as a stimulant. Cocaine can also be used by medical practitioners as a form of anesthetic, however it is considered highly addictive and its use is heavily regulated.
  • Cognitive test: This type of test is an assessment of the cognitive capabilities of humans and other animals. Tests administered to humans include various forms of IQ tests; those administered to animals include the mirror test (a test of visual self-awareness) and the T maze test (which tests learning ability).
  • Community supervision: A post-conviction program that substitutes incarceration with supervised community integration. Community supervision programs can be in lieu of incarceration, in the form of probation, or as a condition of early release from incarceration as a continued part of an individual’s sentence, in the form of parole. Offenders who are granted community supervision typically pose a lower risk to public safety.
  • Controlled setting: This type of setting is controlled for the purpose of comparisons to an experimental setting in a research study. A control is a standard against which experimental observations may be evaluated. In a controlled group study, one group of participants is given an intervention, while another group (i.e., the control group) is given the standard treatment or a placebo.
  • Criminal law: The body of law that defines and prohibits conduct that is harmful to public safety and threatening to the welfare of the general population. Violators of criminal law are prosecuted through the criminal justice system and sanctions that are applied vary based upon the specific crime committed. Criminal law is generally applied when an action is harmful to individuals or public safety, as opposed to civil law which regulates the disputes between private and/or public individuals/entities.
  • Critical tracking task: This type of test is an assessment of the participants’ motor response to a visual stimulus. Participants are asked to control the position of a light bar on a display screen using a steering wheel or joystick. The instability of the bar gradually increases until the subject reaches a threshold of ability to control its position.
  • Culpability studies: This type of study allows for the comparison between a group of drivers who are at-fault versus not at-fault for a particular incident.
  • Dimethyltryptamine: A hallucinogenic drug that can be either naturally occurring or synthesized. Commonly referred to as DMT, it can be inhaled, injected, or ingested to produce hallucinogenic effects. The effects of DMT vary depending upon the specific dosage. DMT is not generally considered addicting or toxic, however it is prohibited in several jurisdictions.
  • Dissociative anesthetic: Dissociative anesthesia is a form of anesthesia characterized by catalepsy, catatonia, analgesia, and amnesia. It does not necessarily involve loss of consciousness and thus does not always imply a state of general anesthesia. Dissociative anesthetics probably produce this state by interfering with the transmission of incoming sensory signals to the cerebral cortex and by interfering with communication between different parts of the central nervous system.
  • Dose-response relationship: This measures the changes or effects in an organism when exposed to different doses of stressors of either the same substance or varying substances in combination with one another. The dose-response relationship in terms of impaired driving measures the impact of alcohol and/or drugs (the stressor) upon the individual’s (organism) driving ability. While the dose-response relation between alcohol and individuals is uniform, the dose-response between individuals and drugs is variable according to the characteristics of individuals.
  • Driving under the influence (DUI): A subset of a driving while impaired (DWI) offence in some U.S. jurisdictions. A DUI is considered a serious criminal offence whereby offenders were in clear excess of the per se limit for a specific substance or their observed behaviour conclusively demonstrates that they were impaired in their driving ability. Generally a DUI is most easily prosecuted for BAC levels that are greater than the pre-determined legal limit, usually in excess of 0.08 but in some jurisdictions the limit is 0.05.
  • Driving while ability impaired (DWAI): A subset of a driving while impaired (DWI) offence in some U.S. jurisdictions. A DWAI offence is considered a lesser offence than a DUI or DWI; however it is generally still a matter of criminal law. DWAIs are usually, although not always, charged when the BAC level is below the legal limit but drivers demonstrated driving behaviour which suggests impairment. In such cases, the onus is on police officers who observed this behaviour to provide sufficient evidence of impaired behaviour as a basis for the charge.
  • Driving while impaired (DWI): An offence whereby one’s ability to safely operate a vehicle was impaired by either alcohol or drugs in many U.S. jurisdictions. DWI offences have varying level of severity but are generally considered a matter of criminal law.
  • Drug recognition expert (DRE): A DRE is a qualified law enforcement official who is trained to recognize impairment in drivers due to drugs other than, or in addition to, alcohol. Interchangeably called a drug recognition evaluator in some jurisdictions, DRE certification requires extensive knowledge of the effects of different types of drugs on the body and officers are required to undergo extensive training prior to receiving this designation, as well as biannual certification.
  • Drug-impaired driving: The operation of a motor vehicle while under the influence of any type of psychoactive substance (illegal substances, prescription medication, over the-counter medication) or a combination of drugs and alcohol that is established or likely to impair abilities required for safe driving. It is a criminal offence and laws used to enforce this type of offence vary as behaviourial laws, per se laws, and zero tolerance laws. All are actively used throughout North American, European, and Australian jurisdictions.
  • DWI court: A specialty court that deals specifically with alcohol-impaired offences. DWI courts deal with alcohol impaired drivers exclusively whereas hybrid courts may deal with alcohol impaired driving as well as various drug offences. Courts are typically post-conviction, and the emphasis of the court is on offender accountability in tandem with rehabilitative measures. The operation and administration of these courts varies from jurisdiction to jurisdiction, and they are more resource-intensive than traditional courts. Court participants are designated high-risk and are either high-BAC or repeat impaired driving offenders.
  • Epidemiological studies: These studies examine the distribution and determinants of health events among specific populations of persons to try to determine the cause of the events.
  • Experimental studies: These types of studies keep certain variables constant while other variables are manipulated in order to determine if the observed results are directly related to the outcome of the experimental manipulations.
  • Felony offence: A serious criminal offence which is subject to long-term imprisonment in excess of one year and can also be punishable by execution in some jurisdictions. Felony offences typically cannot be expunged after any period of time and will remain on a person’s criminal record unless granted an executive pardon. Felony offence sanctions are usually applied to DWI offenders who have committed in excess of a prescribed number of lesser offences, or when they have caused serious injury and/or death.
  • Fine: A monetary fine is usually applied as the least severe sanction that can be given in response to a criminal offence. Fines can range from a few hundred dollars to several thousand dollars depending on the offence, and can be imposed in addition to other sanctions such as probation or short-term incarceration. For DWI offenders, fines are usually applied in addition to other penalties such as licence suspension or enrollment in an interlock program.
  • First offender: Persons convicted of their first criminal offence are designated first offenders. However, research shows that impaired drivers may drink and drive many times before being detected and convicted. Hence the term first offender means the first time a person has been convicted, and not necessarily the first time they committed the offence. Additionally, some jurisdictions allow first impaired driving offenders to plead to lesser traffic offences or to complete a diversion program so their conviction is expunged from their criminal record.
  • GHB: Gamma hydroxybutyrate (GHB) is a central nervous system depressant that can slow brain activity and reduce reaction time. It is colourless and odourless, often being dissolved in alcoholic beverages. GHB has been identified in some jurisdictions as a common narcotic used in instances of sexual assault where an individual is unaware there are consuming it to lessen their resistance to unwanted sexual advances. For this reason many jurisdictions have enacted strict penalties for those who distribute the drug.
  • Hallucinogen: A hallucinogen is a psychoactive agent which can cause hallucinations, perceptual anomalies, and other substantial subjective changes in thoughts, emotion, and consciousness.
  • Heroin: This opiate drug, also known as diamorphine, is often used for recreational purposes. Heroin can be injected, smoked, snorted, or inhaled. It is usually either a white or brown powdery substance. Heroin is considered highly addictive and it is heavily regulated by many states. Although it does have medical applications as a sedative, due to the addicting nature of the drug it is rare that it will be used for this purpose.
  • Hybrid Drug/DWI court: A specialty court that deals with DWI cases as a subset of drug-related offences. Hybrid courts are a combination of a drug/substance abuse court and standalone DWI courts, dealing with all manner of substance abuse-related crimes.
  • Hybrid offences: Most criminal offences in Canada are categorized as hybrid offences which mean the Crown prosecutor can decide whether the offence will be prosecuted as a summary conviction offence or an indictable offence. This decision is often based on the seriousness of the offence as well as any aggravating or mitigating factors.
  • Illicit drug use: Consumption of illegal/prohibited drugs. Common illicit drugs are cannabis, cocaine, heroin, LSD, and methamphetamine.
  • Incarceration: A state of confinement and imprisonment. Incarceration is a common criminal penalty that can be applied for summary conviction (i.e., misdemeanor) and indictable (i.e., felony) offences. For DWI offenders, incarceration can be used as a sanction for both first and repeat offenders of varying lengths depending upon the severity of the crime.
  • Indictable offences: In Canada, more serious offences are deemed indictable offences. Examples include drug trafficking, robbery, aggravated sexual assault and murder. Indictable offences typically have minimum and maximum penalties, which may include life in prison, specified as sentencing guidelines. Defendants have a right to select the mode of trial, including whether a preliminary inquiry is conducted. Convictions are appealed to the Provincial Court of Appeals.
  • Inhalant: These substances are volatile and produce chemical vapors that can be inhaled to induce a psychoactive, or mind-altering effect.
  • Jail: Short-term incarceration facilities for arrested suspects who have not been arraigned, persons awaiting a court appearance, or persons convicted of lesser charges awaiting trial or sentencing. Jails sentences can vary in length from a few days to up to over a year.
  • Ketamine: This substance produces a detachment from reality, distorting perceptions of sight and sound. Ketamine is classified as a dissociative anaesthetic.
  • Licence suspension: A type of sanction whereby an individual’s driving privilege is suspended for a period of time by the licencing authority. The reason for a licence suspension can vary as can the length of the suspension. Licence suspension is a common administrative sanction for an impaired driving offence. Licencing authorities may permit alcohol-impaired drivers to retain their driving privileges with an interlock device installed in lieu of a suspension.
  • LSD: Also known as acid, this substance is a psychedelic drug known for its psychological effects. This may include altered awareness of the surroundings, perceptions, and feelings as well as sensations and images that seem real though they are not. LSD is classified as a hallucinogen.
  • MDMA: Commonly known as ecstasy (E), this substance is a psychoactive drug used primarily as a recreational drug. Desired effects include increased empathy, euphoria, and heightened sensations. MDMA is classified as a hallucinogen.
  • Methamphetamine: A central nervous system stimulant also known as meth, ice, crystal, and chalk. Commonly used as a recreational drug for its euphoric effects, methamphetamine has limited use to treat medical conditions such as attention deficit hyperactivity disorder and obesity in the form of methamphetamine hydrochloride tablets. However this use must be prescribed. More generally, methamphetamine is recognized as a highly addictive drug and is prohibited in many jurisdictions.
  • Millilitre (ml): A unit of measurement being one thousandth of a litre.
  • Misdemeanor offence: A category of criminal offence that is less severe than a felony and may be expunged after a certain amount of time. Summary convictions are often misdemeanor offences for most jurisdictions.
  • Morphine: An opioid pain medication used to treat severe/long-term pain. Morphine is commonly used by medical professionals to help manage pain in patients who suffer from chronic conditions. It can be injected or ingested. Although it can be addictive, it is considered to be extremely safe and effective when administered n proper dosages by a health care professional.
  • Nanogram (ng): A unit of measurement being one billionth of a gram.
  • Narcolepsy: This condition is characterized by extreme drowsiness and sudden onset of sleep.
  • Narcotic analgesic: This substance mimics the activity of endorphins which are substances produced by the body to control pain.
  • New psychoactive substance: Synthetic substances that are designed to mimic the pharmacological effects of existing controlled substances.
  • Nitrates: Although nitrates are used medically, they can also be used illegally as recreational drugs and are often referred to as “poppers”. Poppers cause your veins and arteries to dilate, producing a temporary state of euphoria, relaxation, increased heart beat and a drop in blood pressure. Nitrates are classified as an inhalant.
  • Non-benzodiazepine hypnotics: A class of psychoactive drugs very similar in nature to benzodiazepines. The pharmacodynamics of non-benzodiazepine is almost entirely the same as benzodiazepine drugs and therefore employ similar benefits, side-effects, and risks. However, non-benzodiazepines have dissimilar or entirely different chemical structures and are therefore unrelated to benzodiazepines on a molecular level. Non-benzodiazepine hypnotics are classified as a CNS depressant.
  • Non-compliance: Failure to comply with or complete a criminal justice sanction imposed by a court or supervision agency. For impaired driving offenders non-compliance is usually interpreted as any action that is not in accordance an imposed sanction or condition of supervision.
  • Object movement estimation under divided attention (OMEDA): This is a computerised dual task with two parts. Part 1 allows researchers to obtain an individual’s error in time-to-collision (TTC) estimation. Different target speeds can be simulated, as can various degrees of occlusion. A secondary task is also incorporated in the form of a visual divided attention task. This requires the identification of peripheral duplication of stimuli presented centrally.
  • Opiates: Opiate drugs are derived from the poppy plant, and are therefore non-synthetic. These include opium, morphine and codeine.
  • Opioid: Opioid drugs are synthetic or semi-synthetic derived through chemical synthesis. Opioids function like opiates, and have the same pain-killing effects. Opioids are classified under the narcotic analgesic category.
  • Parole: A post-conviction form of community supervision. Parole is granted to offenders as an early release provision, usually upon the merits of good behaviour and compliance with their previous sanctions. Parole is strictly a post-release supervision program which is granted after serving a longer period of incarceration and is monitored by parole officers. The conditions of parole are generally similar to probation.
  • Passive exposure: Individuals are unintentionally exposed to traceable amounts of drugs or drug residue even though they did not directly consume, ingest, or inhale a drug. For example, persons who inhale cannabis smoke from cigarettes smoked by other individuals in their presence may have detectable levels of THC in their blood despite the fact they have not directly smoked it. The traceable amount of drug is very low.
  • Per se laws: A type of law that makes an act inherently illegal. Alcohol-impaired driving offences often utilize a per se threshold of .08 or .05 grams of alcohol in 100 grams of blood. The presence of alcohol in excess of this limit constitutes an offence which may be proven by demonstrating the driver had a BAC of .08 or greater.
  • Phencyclidine: This substance is used recreationally to produce a feeling of detachment from reality, and can induce hallucinations, anxiety and paranoia. This drug is often referred to as PCP or “angel dust” and is classified as a dissociative anaesthetic.
  • Placebo: A substance or treatment with no active therapeutic effect.
  • Plate impoundment: A form of sanction whereby the licence plate of a vehicle is seized by law enforcement, on behalf of the driver licencing agency in order to prevent an individual from driving. Plate impoundment is viewed as a cost-effective alternative to vehicle impoundment.
  • Post-conviction program: A penalty or program that is imposed upon conviction for an offence.
  • Prevalence: In criminology prevalence can be understood here to mean how often or how frequently a behaviour is committed (i.e. how many people are deterred from offending).
  • Prison: Long-term incarceration facilities which house offenders convicted of serious offences and who received a term of incarceration in excess of two years. A prison sentence may be served in provincial/state or federal facilities managed by a government department or a private prison under contract with the government agency.
  • Probation: A post-conviction program of community supervision involves the supervision of the behaviour of a convicted offender, deemed to be a low risk or moderate risk to public safety. Probation is usually in lieu of incarceration and is used for less serious offences. Probation officers function similar to parole officers.
  • Psilocybin: A hallucinogenic crystalline solid drug that is naturally occurring in 200 species of mushrooms. It has been used for religious/spiritual purposes by many different cultures due to its perception-altering effects on the individual. In general, the effects include euphoria, visual and mental hallucinations, changes in perception, a distorted sense of time, and spiritual experiences, and can include possible adverse reactions such as nausea and panic attacks. Its use is highly regulated and often prohibited in many jurisdictions. Psilocybin is classified as a hallucinogen.
  • Psychomotor: This term refers to the origination of movement in conscious mental activity. Psychomotor learning is demonstrated by physical skills such as movement, coordination, manipulation, dexterity, grace, strength, speed; actions which demonstrate fine motor skills such as use of precision instruments or tools.
  • Quaalude: Also known as methaqualone, is a non-barbiturate sedative-hypnotic substance which can be used to induce sleep but is also widely used as an illicit drug for recreational purposes. Due to health problems associated with overdoses, such as cardiac arrest, the use of Quaalude is highly regulated in many jurisdictions.
  • Recidivism: The commission of additional criminal offences following a first conviction. Recidivism rates are a standard outcome measure in the criminal justice system and in criminal justice research. High recidivism rates are usually an indicator that sanctions are not deterring offending behaviour or that the underlying problems which contribute to offending behaviour are not being addressed.
  • Repeat offenders: Persons convicted of any criminal offence more than once. Repeat offenders can be convicted of one or more offences as part of separate incidents. These offences may be similar in nature or different. For example, a repeat impaired driving offender is someone who has more than one conviction for this offence.
  • Roadside drug testing (RDT): A form of driver screening conducted at the roadside by police to determine whether or not drivers are impaired by drugs. RDT is usually only one step in a process to determine impairment. Subsequent confirmatory tests of biological fluids are usually conducted by a toxicologist to verify screening results.
  • Simple reaction time test: This test involves just one stimulus, and when it appears, subjects performing the test must react with the one response required in this type of experiment.
  • Solvent: A substance that dissolves a solute (a chemically distinct liquid, solid or gas), resulting in a solution. A solvent is classified as an inhalant.
  • Standardized field sobriety test (SFST): A form of driver screening conducted at the roadside by police to determine whether drivers are impaired by alcohol and/ drugs. SFSTs are a battery of validated tests that identify impairment in drivers. Test results can be used as evidence of impairment in court proceedings.
  • Substance abuse education: Education programs that describe the impacts and health risks associated with substance abuse. Substance abuse education may be a post-conviction sanction used in addition to other sanctions to educate offenders about the risks and consequences of substance use and share strategies to prevent or reduce harmful use.
  • Substance abuse treatment: A treatment regime that is designed to help individuals abstain or reduce the harmful use of substances, and understand their behaviour. In the criminal justice system, substance abuse treatment can often be used as a sanction, in conjunction with other sanctions, to help correct offending behaviour and improve the overall health of offenders.
  • Substance abuse: The excessive or harmful use of addictive substances that can result in misuse, abuse or dependence. Substance abuse can have accompanying health and public safety issues that have lead jurisdictions to regulate the sale and consumption of specific substances and/or prohibit their use.
  • Summary conviction offences: In Canada, less serious criminal offences are deemed summary conviction offences. The maximum penalty for a summary offence is usually a $5,000 fine and/or six months in jail. Some summary offences have higher maximum sentences and in some instances a breach of a probation order may be considered a summary offence. Persons are not fingerprinted by police for summary conviction offences, and cases may be appealed to the Superior Court of the Jurisdiction.
  • Synthetic cathinones: Synthetic cathinones are a man-made chemical related to the khat plant, a shrub grown in East Africa and Arabia. Synthetic cathinones are often referred to as “bath salts”, and are consumed for their stimulant properties.
  • THC: Tetrahydrocannabinol, or more precisely its main isomer-trans-Δ⁹-tetrahydrocannabinol, is the principal psychoactive constituent of cannabis.
  • Time Wall test: Participants estimate when an occluded, moving object reaches a target point.
  • Toluene: This substance is a colorless, water-insoluble liquid with a smell that is often associated with paint thinners. Toluene is classified as an inhalant.
  • Tower of London task: This test is used in applied clinical neuropsychology to specifically assess executive functioning to detect deficits in planning, which may occur due to a variety of medical and neuropsychiatric conditions. The test consists of two boards with pegs and several beads with different colors. The examiner uses the beads and the boards to present the subject with problem-solving tasks.
  • Vehicle impoundment: A post-conviction sanction for vehicle related offences whereby the physical vehicle is confiscated by the state and held at a predetermined location. Vehicle impoundment is often seen as a last resort for DWI offenders given that it is fairly costly to collect and store offender vehicles.
  • Vigilance: This is the action or state of keeping careful watch for possible danger or difficulties.
  • Wisconsin Card Sorting task (WCST): This is a neuropsychological test of “set-shifting” (i.e., the ability to display flexibility in the face of changing schedules of reinforcement). A number of stimulus cards are presented to subjects who are told to match the cards, but are not told how to match them; however, he or she is told whether a particular match is right or wrong.
  • Young/juvenile offenders: Offenders who, at the time of their offence, were below the age of majority that legally determines adulthood. In most jurisdictions this age is 18 however in some jurisdictions it can be as high as 21.
  • Zero tolerance laws: Laws that prohibit any amount of an impairing substance in the body of a driver who is operating a vehicle.  The value may be zero or less than a preset threshold close to zero. Zero tolerance laws are a form of per se laws. For drug-impaired driving, zero tolerance laws often have limits set slightly above zero to account for prescription medication and instances of passive exposure, neither of which would likely impair individuals.