In Illinois, U.S.A. a driver may not operate a motor vehicle while under the influence of cannabis prescribed for medicinal purposes and may not transport medicinal cannabis in a vehicle unless it is stored in a tamper-evident container and kept in an area that is inaccessible while the vehicle is in motion. If a police officer stops a vehicle driven by a person who holds a medical cannabis registry card and the officer has reasonable suspicion to believe the person is impaired by the use of cannabis, the driver must submit to field sobriety testing. Refusal to submit to testing or failure of the field sobriety tests will result in the suspension of the persons license. Driving while impaired by the use of cannabis, or driving with an open container may result in the loss of driving privileges as well as the revocation of the driver's medical cannabis card. In randomly selected drivers throughout Europe, results showed that the most frequently detected illicit drug in traffic was cannabis THC had the highest rise in use in weekend night times where 12.6 percent of participants tested positive for THC. We understand how driving is often an essential tool for maintaining and active independent lifestyle but it is advised to not get intoxicated on cannabis and then drive. Initially, motor skills are impaired as is proper judgement. In a test in the USA of over 10,000 drivers involved in crashes were 1.25 more likely to test positive for THC than those who were not impaired by cannabis but because of other factors including alcohol consumption, according to these studies, increased risk for crash under the influence of THC can not be determined. In a Colorado test, In the years 2013 and 2014, over 25 percent of fatalities involved drugged drivers. In a Canadian test of over 13,000 fatalities, of the drug classes tested, cannabis was the second most common among traffic fatalities precedes only by depressants and went ahead of narcotic drugs. The data is also tainted by the fact that many cannabis users also use alcoholic beverages or other drugs.
a recent meta analysis and large review agree on association of cannabis with impaired cognition during acute intoxication and even the "clean" un-intoxicated state in long term users. Meta-analysis of experimental driving simulator studies on impaired drivers resulted in these studies pointing to attention deficit, and decreased psychomotor functioning. They also agree that there is a substantial evidence statistical association between cannabis use and increased risk of motor vehicle accidents.
There are many different ways of testing for intoxication but testing for cannabis intoxication is varied by the fact that saliva tests show cannabis positive for up to a month. Everetts sensitivity test of 38 percent which means that just 38 percent of those who consumed cannabis were detected by testing body fluids is far from sufficient for routine use by law enforcement authorities.
Field sobriety tests are often administered and are the main way for a police officer to arrest a person who may seem to be under the influence.
It is safe to say, people who consume cannabis on a regular basis should wait at least a few hours before attempting to use a motorized vehicle. In some states and countries, laws differ. Some have zero tolerance whereas some places have intoxication levels in the blood. There is absolutely much evidence to show that cannabis use impairs cognition, rate of response to an object unexpected on the road, rate of response to breaking at a changing light and many other variables all point to the fact that drugged driving is unsafe for both the driver and the general public that the person may encounter. }