Have you been arrested for impaired driving because you drove under the influence of marijuana? Unlike drunk driving, which can be measured by blood alcohol levels, there is no legal limit for driving under the influence of marijuana. Rather, the police officer normally testifies to a variety of factors indicating the influence of the marijuana. The standard test for marijuana is a urine test, but there can be a whole host of problems associated with such a test, including how long marijuana is detectable in a person’s urine, which can be a considerable period. For more information about defending a charge of driving under the influence of marijuana, contact an experienced attorney in your area.