As more states legalize marijuana for medicinal or recreational use, law enforcement agencies throughout the country are struggling with how to determine how much people can have in their system before they can be charged with driving under the influence. The issue is only going to become more widespread. November 2016 election will include the issue of legalizing marijuana on the ballot in as many as 11 states.
Nevada is one of six states that currently has specific legal limits for the level of THC that people can have in their blood while behind the wheel. THC is the chemical that causes the "high" when using marijuana. Another nine states make it illegal to have any amount of THC is your system while driving.
One of the challenges, particularly for people who use the drug regularly to ease pain or other medical issues, is that THC can remain in a person's system for weeks after they've used marijuana and are no way impaired by it. As one professor who studies drugs and criminal policy notes, "A law against driving with THC in your bloodstream is not a law you can know you are obeying except by never smoking marijuana or never driving."
Another issue is that law enforcement agencies still don't have the kind of roadside tests that are used to determine blood-alcohol content. Further, marijuana can impact people very differently.
A study by AAA also criticized the current efforts being used to curb driving under the influence of marijuana. The head of AAA said that the presence of marijuana simply can't be measured the way alcohol is. He called the methods "flawed and not supported by scientific research."
If you are charged with driving under the influence of marijuana, it's essential to have sound legal guidance. The amount of marijuana in your system may be more difficult to measure than the level of alcohol. However, people can nonetheless be convicted of driving while under the influence of the drug even if they were long past the point of impairment.
Source: ABC 7, "Laws on Driving While Impaired by Marijuana Questioned in AAA Study," May 10, 2016