Illinois has legalized the use of medical marijuana, but the law is relatively restricted compared to other states. Some of those states where the use of marijuana is allowed for both medical and personal use have tests that they use to determine whether a motorist is impaired by THC, the chemical that produces a high in marijuana users. The AAA Foundation for Traffic Safety has criticized those tests, however.

The organization has found that there is little to no scientific basis for them. The test appears to be unable to determine whether or not a driver is intoxicated, and is therefore a flawed standard for the presumption of guilt or innocence.

The AAA notes that laws in some states mandate blood testing for THC and deciding the level of intoxication based on the measurement of THC levels alone. The advocacy group feels that this is inappropriate. In its view this puts people who were not intoxicated at legal risk while allowing those who could not operate their vehicle safely to go free. It feels that the laws should instead require observation by trained authorities following a checklist-based system.

A DUI charge can be issued not just for alcohol, but for marijuana or another drug that causes impairment. A conviction on such a charge can lead to serious consequences, in some cases including incarceration. As a result, those who have been taken into custody for driving while impaired may want to have the assistance of a criminal defense attorney in trying to defeat the prosecution’s case, such as by challenging the validity of the traffic stop that led to the arrest.

Source: CBS News, “Tests for driver impairment by marijuana flawed: AAA”, May 10, 2016