While many states have developed marijuana laws, Maine could soon join 5 other states that have legal limits on the amount of THC that can be in someone's blood while driving. A bill currently being debated in the Legislature's Criminal Justice and Public Safety Committee would set the legal limit to 5 nanograms of THC per 100 ml of blood. Some are wary of setting the limit so low while the science is not exact. Daily tokers could have more than 5 nanograms of THC in their blood while sober, but other testing methods are not yet helpful. Research suggests that cannabis does not impair drivers nearly as much as alcohol and does not lead to making risky choices while behind the wheel.
There is no simple roadside test for marijuana similar to the breath test used to determine blood-alcohol content. Police officers currently use a drug recognition exam on the roadside to detect impairment from drugs. But some say officers need better tools to stop drugged driving as the culture becomes more accepting of marijuana use.