NerdWallet: A Few Hundred Good Reasons to Avoid a Marijuana DUI

Unlike laws for drunk driving limits, which are fairly uniform across the U.S., regulations on driving with marijuana in your system vary from place to place. Six states enforce specific limits on how much THC, the main psychoactive element in marijuana, drivers can have in their blood. Twelve others have zero-tolerance policies. Most states, however, still lack concrete marijuana laws for motorists, according to the Governors Highway Safety Association.

The point at which stoned drivers are considered “impaired” fluctuates by…