PinIn Minnesota, it is prohibited to operate a motor vehicle with a blood alcohol concentration of .08 percent or higher. Operating a vehicle under the influence of drugs, particularly marijuana, is a different matter.

State law enforces a zero tolerance policy for individuals found operating a motor vehicle with any amount of controlled substance of Schedule I or Schedule II in their blood. This means that the person driving does not actually need to be impaired in order to be charged with DWI. It is important to note that in Minnesota, along with Virginia and North Carolina, this zero tolerance policy does not apply to marijuana or to marijuana metabolites.

For several decades, advocates of marijuana have debated on the effects of marijuana on a person’s driving ability. Numerous studies have been conducted on the relationship between driving impairment and marijuana use, and many of them are contradictory and inconclusive. Many reports show that drugged driving increases the likelihood of a car crash occurring, but others insinuate that it does not. 

When it comes to driving under the influence of marijuana and other substances not found in Schedules I and II, a law enforcement officer will first have to determine that the drug consumption substantially impaired the driver’s ability to operate the vehicle safely. It must be proven that the driver was so impaired by marijuana that he or she was unable to exercise the same amount of caution that a sober person, using ordinary care, would have under similar circumstances.

This can be difficult to prove in many instances, however, because marijuana has a relatively short high. It can also stay in a user’s system for up to 30 days, which means that a person may test positive for marijuana even if he or she did not smoke it prior to or while driving a vehicle.

Many assume that like alcohol, cannabis impairs the coordination, perception, sense of judgment, and reflexes needed to operate a vehicle safely. Findings from various studies though, including some from the U.S. National Highway Transportation Safety Administration, do not always support this opinion.

According to these studies, drunken drivers drive differently from those high on marijuana. Motorists under the influence of marijuana have a tendency to drive slower and have accident responsibility rates that are lower than those of drug free drivers. Drunken drivers operate their vehicles faster than normal and are known to overestimate their skills, while the opposite is true for drivers impaired with marijuana. The shortfalls in driving stoned only become more apparent when the driver faces an unexpected situation or is handling multiple tasks at once.

Research on alcohol and marijuana effects were conducted using a fully interactive simulator, and results showed that marijuana only had an occasional effect on an individual’s impairment, while alcohol consistently and significantly caused impairment. Studies also showed that alcohol intake increased the number of accidents and speeding tickets issued, but no such results were noted for marijuana use or combined use of alcohol and marijuana.

Due to the complex and varying effects of drugged driving, many states have difficulty developing and implementing DUI laws on marijuana that are fair and effective. This is why researchers continue to find a solid connection between marijuana DWI and elevated accident risk. 

Source: 2013 Minnesota Statutes, published