Like many states, Montana has legalized (with certain restrictions) the recreational use of marijuana. However, driving while impaired by marijuana or any other drug is still very much illegal. This article explains when the use of drugs and other substances—legal or otherwise—can result in a drugged driving conviction.
Montana has two types of drugged driving: driving under the influence of drugs (DUID) and driving with an unlawful THC content (per se DUID).
Driving under the influence. A driver is considered to be under the influence of drugs if his or her ability to safely operate a vehicle has been diminished. To prove a drug DUI at trial, the prosecutor might use evidence of impairment such as the arresting officer's observations, blood test results showing what drugs were in the driver's system, and expert testimony related to the intoxicating effects of the relevant drug or drugs. The fact that the driver was prescribed the drug isn't a valid defense to a DUI charge.
Per se DUID. A driver can also be convicted of DUID if his or her blood contains 5 nanograms of THC per milliliter. To be convicted of a per se DUI, the person need not show actual signs of impairment. A registered marijuana cardholder or producer who is convicted of a DUI is subject to registration revocation.
The penalties for a per se DUID and impairment DUID are roughly the same as they are for standard drunk driving convictions.
First offense. A first-offense DUI conviction is a misdemeanor and normally carries up to six months in jail, $600 to $1,000 in fines, and a six-month driver's license suspension. Drivers convicted of a DUI based on impairment (as opposed to THC or alcohol concentration) must serve at least 24 hours in jail before release. Probation requires completion of a chemical dependency assessment and education course and may require an ignition interlock device (IID) or other form of sobriety supervision. A probationary license (with an IID) is available to permit driving during the suspension period.
Second offense. A second DUI conviction within ten years will result in five days to one year in jail, $1,200 to $2,000 in fines, and a one-year license suspension. An impairment DUI conviction requires the driver to spend at least seven days in jail before probationary release. The offender must also complete the chemical dependency assessment and participate in treatment and the 24/7 sobriety program for one year. A probationary license is available after 45 days of license suspension. The court is also authorized to order IID installation or vehicle forfeiture instead of monitored sobriety.