Impairment detection technology

Impairment detection technology (IDT) refers to tools and systems designed to assess whether an individual is functionally impaired at a given moment, regardless of the cause. Unlike drug and alcohol tests that detect substances or their metabolites in the body, IDTs evaluate real-time cognitive or physical performance to identify active impairment.^[1]^[2] These systems are relevant where safety is critical, such as workplaces and law enforcement.^[3]^[4]

IDTs do not identify the specific cause of impairment, such as drug use, fatigue, or illness, but instead detect behavioral or physiological markers like slowed reaction time, poor coordination, or eye movement abnormalities.^[5]

Interest in IDT has increased as workplaces and law enforcement agencies address the limitations of traditional drug testing methods. The legalization of cannabis has underscored challenges associated with metabolite-based tests, which can yield positive results days after use, even when the individual is no longer impaired.^[6] Studies indicate that tetrahydrocannabinol (THC) levels in blood or saliva do not reliably correlate with functional impairment, as frequent users may retain high THC concentrations without experiencing intoxication, and metabolites may remain detectable long after psychoactive effects have ended.^[6]

Types

IDTs assess an individual’s functional state in real time by monitoring cognitive performance or physiological responses. These technologies fall into several categories:

Oculomotor

These systems analyze involuntary eye movements and pupil responses, such as nystagmus or delayed reactions to detect impairment. Devices like Gaize’s VR headset use eye-tracking sensors and machine learning to detect intoxication based on ocular behavior.^[7]

Psychomotor

Digital tests measure reaction time, attention, and coordination to detect cognitive deficits due to fatigue or substances. The Psychomotor Vigilance Test (PVT), widely used in fatigue studies, has been shown to detect alertness lapses in professional drivers.^[8]

Physiological

Wearables and in-vehicle systems detect drowsiness or impairment by monitoring eye blinks, head movement, or steering behavior. Some advanced devices use brain-scanning methods like functional near-infrared spectroscopy (fNIRS) to identify cannabis related changes in brain activity.^[6] From 2024, the EU mandates drowsiness detection systems in all new vehicles to enhance road safety.^[9]

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Legality

Impairment testing is legally distinct from traditional drug testing, as a result, these tests often fall outside the scope of U.S. drug testing regulations.^[10]

In the United States, legislative changes such as California Assembly Bill 2188 limit employment decisions based on non-psychoactive cannabis metabolites, encouraging the adoption of functional impairment assessments.^[11]^[12] Most impairment detection tools do not collect biometric templates or personally identifiable data to comply with privacy laws like the Biometric Information Privacy Act.^[13]

Legal precedent such as The T.J. Hooper case suggests that employers may risk liability for failing to adopt reasonable safety measures like impairment testing in safety-sensitive environments.^[14]

In Canada, workplace testing must align with human rights legislation, focusing on job relevance and minimal intrusiveness.^[15] The Canadian Supreme Court’s 2013 decision in Irving Pulp & Paper emphasized that random testing requires evidence of significant safety risk.^[16] Canadian privacy authorities also recommend limiting personal data collection during testing.^[17]