Almost two years into the era of legal recreational marijuana in California, many drivers remain unsure about how marijuana use affects driving, and how the authorities treat the issue. And these drivers aren’t alone in their confusion: The authorities have been struggling to come up with the appropriate response.

To better understand the issues involved, first remember three important points. First, studies show that drugs including marijuana products can slow response time and make drivers unsafe behind the wheel. Second, note that it is illegal to use cannabis products while driving, or to keep them in an open container in the cabin of a car, just as it is illegal to have an open bottle of alcohol in the cabin of a car.
Third, note that the penalties for those found guilty of driving under the influence of marijuana are essentially the same as those faced by people who are found guilty of DUI under the influence of alcohol.

The biggest difference with how the law treats alcohol-impaired driving and marijuana-impaired driving lies in how police test for the two intoxicants. Police have several ways of measuring alcohol intoxication, but some of the most important are Breathalyzer devices and blood draw tests. With these, they measure a driver’s blood alcohol concentration, or BAC. Anyone with a BAC of 0.08% or higher is legally presumed too drunk to drive.

There is nothing similar to this so-called legal limit for THC, the psychoactive ingredient in marijuana. Likewise, the technology for chemically testing THC intoxication is in its early stages. Instead, police generally rely on their own observations for evidence that a driver is too high to drive. For instance, if they pull over a driver they think is driving erratically, they may report that the driver had red eyes and smelled like marijuana smoke. This report will then be used as evidence in the driver’s prosecution.

A good DUI defense lawyer helps clients attack the evidence against them as best as possible and helps them find the best resolution they can.