With an increasing number of states legalizing marijuana medicinally, recreationally, or both, questions arise as to how—if at all—this legalization will impact DWI law. Given that more states are legalizing marijuana begs the question of how law enforcement officers are supposed to detect drivers who are under the influence. Additionally, questions are raised as to what it means to be over the limit in this context.
Effects of legalization in Washington and Colorado
A 2016 CATO Institute Policy Analysis examined the impact of state marijuana legalizations on several factors. With respect to road safety and DWIs specifically, this report evaluated opposing prior literature that suggested: first, that marijuana impairs driving ability and, thus increases accident incidence; and second, that marijuana legalization improves traffic safety because marijuana is a substitute for alcohol and may even improve the driving of persons who use marijuana to alleviate chronic pain.
Many governments—at federal, state, and local levels—warned that legalization marijuana would increase traffic accidents significantly. However, the data vary. According to the AAA Foundation, when Washington state legalized recreational marijuana, the number of fatal automobile accidents increased. Among the key findings included that between 2010 and 2014, 303 drivers (10% of all drivers involved in fatal accidents) had detectable levels of THC in their blood at the time of the accident with or without alcohol and/or other drugs. Additionally, after recreational marijuana was legalized, the proportion of DWI drivers who tested positive for THC increased significantly nine months after the new law went into effect.
However, data from Colorado demonstrate that highway fatalities were at historic lows following legalization. Further, marijuana legalization in Oregon and Alaska also showed no discernible increase—and even slight decreases—in traffic fatalities.
Marijuana legalization and changing laws
Most of the states which have legalized marijuana have not changed their DWI laws. Generally, these laws are of two types: per se and impairment. Per se DWI laws require the prosecutor to prove the driver had a BAC of .08 or greater at the time s/he was stopped. Impairment need not be proven as the presence of the substance in question in his/her system is usually enough to secure a conviction. However, most of these laws apply only to alcohol consumption as marijuana is not measured in BAC. Thus, a motorist who is driving while under the influence of marijuana cannot typically be convicted of a per se DWI.
On the other hand, impairment DWI charges do, in fact, apply to marijuana use in that these laws focus on the effect of the drugs on the driver, not on the actual amount of the drug in the driver’s system. Further, impairment DWI laws do not limit whether the drug in question was illegal or legal. Thus, even if a motorist has legally ingested marijuana, if s/he is impaired and drives, s/he can be convicted of DWI.
Proving whether impairment exists and its degree is the difficult part. Complicating matters is that each state has its own degree of impairment requirements. Currently, Minnesota’s laws are zero-tolerance with respect to Schedule I and Schedule II controlled substances (including marijuana.) Thus, if you are driving while impaired—from any substance—you could be charged with a DWI.
According to one San Diego criminal defense attorney, determining what it means to be “too high to drive” given that people are of different sizes and have different tolerance levels can be difficult. She asks where does one start setting this amount? What is the marijuana equivalent of .08 blood alcohol concentration (BAC)? She stresses that until science “catches up,” police must rely on traditional roadside sobriety tests to determine intoxication.
Regardless of the fact that marijuana is legal in many states, it is still illegal to drive while under the influence.
You can check out our earlier article on potential marijuana legalization in Minnesota here.