With recent laws that legalized the use of cannabis, car accidents involving drivers high on marijuana have risen by as much as 300 percent.

Cannabis-Related Car Crashes
While the dangers of drunk driving are well-known, new studies show that driving while high on marijuana is just as dangerous. Between 2010 and 2013, the number of marijuana-related car crashes in the United States jumped by 300 percent. As states continue to legalize the use of cannabis, car accident lawyers are seeing a significant rise in impaired driving accidents around the country.
In a AAA study that focused on cannabis use among drivers in Washington state, there was a clear increase in car accidents following marijuana legalization. Washington legalized the recreational use of marijuana in 2012. In the next five years, there was a significant rise in drivers who tested positive for tetrahydrocannabinol (THC), the main component in marijuana that produces its known psychological effects.
Study researchers focused on three areas of intoxicated driving: (1) weaving in and out of lanes; (2) speed of weaving; and (3) the number of times a car left the lane. In conclusion, results showed that weaving patterns actually increased in frequency in drivers using marijuana. Blood levels of tested drivers averaged 13.1 ug/L THC, which is equivalent to a driver who has a .08 blood alcohol concentration (BAC). Although .08 BAC is legal in most states, 13.1 ug/L THC is more than double the legal limit of 5 ug/L THC in Washington where the recreational use of marijuana is legal.
Currently, six states – California, Hawaii, Illinois, New Hampshire, Rhode Island, and West Virginia – routinely perform toxicology tests on drivers involved in fatal car crashes. Data shows that alcohol-related fatalities remain constant at about 40 percent, but drug-related fatalities increased by more than 28 percent, with marijuana cited as the most common drug involved in fatal car accidents. If a driver is under the influence of alcohol, a fatal car crash is 13 times more likely than the risk for a sober driver. If a driver is under the influence of both alcohol and marijuana, the risk of a fatal crash is 24 times higher.
In Illinois, cannabis is legal for both medical and recreational use by adults age 21 and older. On June 25, 2019, Governor JB Pritzker signed a bill into law legalizing recreational marijuana use and sale in the state, making Illinois the 11th state to legalize marijuana.