The effects of specific drugs on driving skills differ depending on how they act in the brain. For example, marijuana can slow reaction time, impair judgment of time and distance, and decrease coordination. Drivers who have used cocaine or methamphetamine can be aggressive and reckless when driving. Certain kinds of prescription medicines—including benzodiazepines and opioids—can cause drowsiness, dizziness, and impair cognitive functioning (thinking and judgment). All of these effects can increase the chances of vehicle accidents.

Research studies have shown negative effects of marijuana on drivers, including an increase in lane weaving, poor reaction time, and altered attention to the road. Use of alcohol with marijuana makes drivers more impaired, causing even more lane weaving. Some studies report that opioids can cause drowsiness and impair thinking and judgment. Other studies have found that being under the influence opioids while driving can double your risk of having a crash.

For these reasons, many states have laws making it a criminal offense to operate a vehicle under the influence of or while impaired or intoxicated by legal or illegal prescription or recreational drugs, for example—known as drugged driving or driving under the influence of drugs (DUID). And a driver’s use of a prescription medication is not a defense to operating a vehicle while impaired or intoxicated by the medication.

In many states the DUI/DWI statutes are broad enough to prosecute a driver who is under the influence of or impaired or intoxicated by prescription or recreational drugs—as well as alcohol or any other substance, including an inhalant with a vapor-releasing substance. And at least 15 states have per se (pronounced purr-say) drugged driving laws that make it a criminal offense to drive with any detectable amount of certain drugs in your system, or with a minimum prohibited amount of certain drugs, as provided in the state’s statutes. These states include Arizona, Delaware, Georgia, Illinois, Indiana, Iowa, Michigan, Minnesota, Nevada, Ohio, Pennsylvania, Rhode Island, Utah, Virginia, and Wisconsin.

Drugged driving laws are generally located in a state’s statutes—often in the penal code or criminal code.

In Utah, driving under the influence of drugs (DUID) is a criminal offense, as it is in many other states. This includes the use of illegal drugs, prescription medications, and over-the-counter substances that impair driving abilities. Utah law recognizes the diverse effects of different drugs on driving skills, such as delayed reaction times, impaired judgment, and decreased coordination. The state has per se drugged driving laws, which make it illegal to operate a vehicle with any detectable level of certain prohibited drugs in the driver's system. This means that a driver can be charged with DUID even if they are not exhibiting signs of impairment but have a detectable amount of certain drugs in their body. Additionally, using prescription medication is not a valid defense against a charge of operating a vehicle while impaired. Utah's DUI statutes are broad and encompass driving under the influence of any substance that can impair driving, ensuring that drivers who are under the influence of drugs are subject to legal penalties.