Everyone knows you can get a DUI for driving under the influence of alcohol. But do DUI laws also apply to driving under the influence of marijuana? And does it matter if you used marijuana legally?
Driving under the influence of marijuana is illegal in every state. And even if your marijuana use was lawful—because recreational marijuana use is legal in your state or you have a medical prescription—it doesn't mean you can't be convicted of a marijuana-related DUI.
Driving with a blood alcohol concentration (BAC) of .08% or more can get you convicted of a "per se" DUI. But some states also have per se DUI laws that apply to marijuana. In other words, these states have laws that prohibit driving with a certain concentration of THC (the psychoactive ingredient in marijuana) in your system. And the DUI laws in every state make it illegal to drive while actually impaired by marijuana (or any other drug).
Per se marijuana DUIs. To prove a per se marijuana DUI, a prosecutor would typically need to produce blood test results showing the driver was over the legal limit. If a prosecutor is able to do that, it doesn't matter whether the person's ability to drive was actually affected by marijuana. A per se conviction is based just on the amount of THC in the driver's system.
Impairment DUIs. While all states have impairment DUI laws, they don't all define "impairment" the same way. Proof that the marijuana (or other substance) affected the driver in "any way" is enough for a conviction in some states (such as Maine). But in most states, the prosecution must show a "substantial" or "significant" effect from the substance ingested (Arkansas and California are two of the states in this camp). Evidence of impairment usually comes from the arresting officer's observations of things like:
However, impairment and TCH levels are just part of what prosecutors must prove to get a DUI conviction.
Zero-tolerance laws for underage drivers. Some states (like South Dakota) have zero-tolerance laws that apply to underages drivers. In these states, an underage driver can get in trouble for having any measurable amount of THC in his or her system.
Generally, the penalties for a marijuana-related DUI are the same as those for an alcohol-related DUI conviction. The consequences of a first offense might include:
However, state laws vary and lots of factors can influence sentencing. For instance, an offender who's never been in trouble before will likely be treated more leniently than an offender with a long criminal record. And enhanced penalties typically apply for DUIs that involve injuries or deaths.
Anytime you're arrested for driving under the influence, it's a good idea to get in touch with a qualified attorney. An experienced DUI lawyer can tell you how the law applies to the facts of your case and help you decide on the best way to defend against the charges.