In Colorado and other states where medicinal or recreational marijuana has been legalized, police officers are changing the way they conduct traffic stops where they suspect impaired driving. They plan to perform a variety of tests that help prove a driver is intoxicated with THC since it is tough to prove with just a blood test. They may record information related to driving behavior, smell, dilated pupils, and the presence of marijuana paraphernalia.

Before the legalization of pot in some states, a traffic stop involved a sobriety test and perhaps a breathalyzer. If marijuana was discovered, an officer would add a possession charge. Now that cannabis is legal, they will need to use more creative ways to discover if that marijuana has actually been ingested by the driver. That's why many states are training officers to recognize the signs of cannabis use.

The number of actual drivers who are impaired by cannabis in states where the drug is legalized is difficult to determine. In Maine, drivers involved in fatal accidents have not been tested for marijuana. In Colorado, between 30 and 50 drivers intoxicated above the legal cannabis limit are involved in fatal accidents per year. This is less than 10 percent of the total traffic fatalities in the state every year.

Drivers accused of operating a vehicle under the influence of marijuana or alcohol have the right to representation from an attorney. A lawyer may mount a drunk driving defense that accounts for the constitutional rights of the driver. This means making sure evidence at the scene of the traffic stop is gathered legally and that the officers adhere to the due process rights of the driver. In some cases, negotiating with a prosecutor to get a plea deal may be the best possible option.