Decriminalizing and making marijuana legal is a growing trend throughout many states. However, even when legal, it is still an offense to drive under the influence of marijuana. As a Massachusetts OUI Defense Attorney, this creates problems as it is much more difficult to measure the presence of marijuana in the system opposed to alcohol. With an alcohol OUI charge, registering a .08 or higher will create a presumption that the driver was operating under the influence. There is not really a “magic number” such as this for marijuana and has created difficulty in OUI cases involving drugs. Colorado has recently taken on the challenge of trying to create a threshold for marijuana.
The effects marijuana have on driving is not as clear as the effect alcohol has which was a problem for Colorado law makers. However, they were determined to find a number to put on the amount of marijuana in a drivers system in order to make it more like an alcohol OUI. Colorado concluded that a driver will be assumed to be impaired if a blood test shows THC in five or more nanograms per milliliter. When a blood test shows this amount of TCH, it will be the same as blowing a .08 in a drunk driving charge.
Similar bills creating a standard like this for marijuana use have been met with some resistance. This is due to the small amount of research done on the effect marijuana has on driving and the intrusive nature of taking a suspect in for a blood test. Research has shown that the more marijuana used, the worse a driver will be performed. This is really the only data available and more will be available late this year.