Driver Impairment

Driving research on drivers impaired by alcohol, drugs, medications, or a medical, neurological, or physical condition.

What's here. Substance work (alcohol, cannabis, illicit_drugs, opioids, prescription_meds, polydrug) alongside impairment arising from the driver's own condition: medical_conditions, post_concussion, physical_impairment, cognitive_impairment, and drowsy_as_impairment, which treats sleepiness as an impairment state. The shelf is organized around what the driver was impaired by, not around detection hardware or legal thresholds.

What isn't here.

• cognitive distraction from phone calls, conversation, or other secondary-task load — Driver Distraction. That subcategory is `cognitive`, which is easy to mistake for `cognitive_impairment` here. Use this category when the deficit is something the driver brings to the wheel, and Driver Distraction when it is load imposed by a concurrent task.
• dementia, mild cognitive impairment, and fitness-to-drive assessment in older drivers — Age & Experience. Age & Experience is the strongest co-occurring neighbour. Clinical decline framed as an aging or licensing-fitness question was filed there, so search both branches before concluding the work is missing.
• DUI enforcement, per se BAC limits, checkpoints, and drug-driving law — Policy & Enforcement. Papers here characterize the impaired driver. Papers evaluating statutes, sanctions, or enforcement programs sit on the policy shelf even when the substance is the same.