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What Are the Five Kinds of Driving Impairment?

Human error plays into over ninety percent of all vehicle collisions. Driving impairment factors heavily in human error. Twenty-nine people die every day across the country in alcohol impaired vehicle crashes alone. That means a person dies about every fifty minutes. In fact, alcohol related car crashes cost over $44 billion annually.

The Scope of the Problem (as of 2016)

  • Almost 30% of all traffic related deaths in the US involved alcohol impaired drivers.
  • 17% of children under 14 years who were in a crash involved an alcohol impaired driver.
  • Over a million drivers faced arrest for driving under the influence of alcohol or narcotics. Only one percent of self-reported incidents of alcohol impaired drivers face arrest.
  • Legal and illegal drugs factor in about 16% of crashes.
  • Marijuana appears in the system of 13% of night and weekend drivers.
  • Although marijuana users crash 25% more often than drivers with no marijuana in their systems, factors like age and gender explain the increased risks.

Not all driving impairment is as a result of alcohol or drugs. The National Highway Traffic Safety Administration identified five distinct kinds of driving impairment.

  • Medical Conditions
  • Distractions
  • Alcohol
  • Drugs
  • Fatigue

Medical Conditions

Chronic medical conditions can cause sudden, unexpected changes in consciousness.

  • Mini Strokes or Transient Ischemic Attacks (TIAs)
  • Epilepsy
  • Diabetes
  • Heart Disease

Some individuals with these chronic conditions do not drive. Their medical ineligibility for a drivers’ license reduces risks for everyone on the road. If they do drive, their liability for damages increases if they experience a medical episode based on a previous diagnosis and a crash occurs. When a doctor advises against driving, getting behind the wheel anyway – even with a valid license – demonstrates the lack of ordinary care.


Cell phones contribute to the distracted driving crisis as they demand the driver’s attention. A cell phone combines every one of the three types of distracted driving.

  • Cognitive distraction occurs when something takes the driver’s mind off driving.
  • Visual distraction happens when drivers take their eyes off the road.
  • Manual distraction ensues when the driver takes at least one hand off the steering wheel.

Distracted driving also includes using hands free phones as cognitive and visual distractions. Eating, talking to the passengers in the car, and applying make-up while looking in the rear-view mirror reflect common, dangerous, distracted driving examples.


Alcohol clouds driver judgment and impairs critical motor skills. Legal intoxication levels require blood alcohol levels of .08, but driving impairment occurs at lower levels. Just one drink affects some motor skills and reaction times.

A driver convicted of driving intoxicated shows negligence. Circumstantial evidence like erratic driving or bloodshot eyes also prove negligence. This all supports the victim’s case.


Many types of drugged drivers are on the road. In some areas, the drugged drivers are more common than drunk drivers.

  • Some over-the-counter drugs like Sominex or NyQuil impair a driver’s ability. Many individuals push themselves through to perform daily tasks, even when they are under the influence of these medications.
  • Street drugs like heroin and cocaine impair the judgment and reflexes of the driver. Some individuals try to operate their lives in a normal way while using these illegal drugs.
  • Prescription drugs such as Oxycontin and Xanax help many people, but they still impair driving. Warnings on the prescription bottles caution patients not to drive or operate heavy machinery while taking the medicine.


Fatigue affects the brain much the same way as alcohol. After eighteen hours awake, the fatigue changes the brains reactions to the same level as driving with a .05 blood alcohol level.

Fatigue has no test, so plaintiffs use circumstantial evidence to prove liability. Erratic driving provides excellent evidence, plus any statements from the driver about feeling tired.

As a plaintiff, the details behind the different types of the driver’s impairment remain important for your case.