Montana’s drugged driving law is located at Montana Code Annotated Section 61-8-401. It states, "It is unlawful and punishable … for a person who is under the influence of … a dangerous drug to drive or be in actual physical control of a vehicle within this state, or any other drug to drive or be in actual physical control of a vehicle within this state." "Under the influence" means that as a result of taking into the body alcohol, drugs, or any combination of alcohol and drugs, a person's ability to safely operate a vehicle has been diminished.
In other words, in Montana it’s a crime to drive while under the influence of a drug. No blood testing standard is established in Montana – that is, there is no fixed amount of drugs within the blood system that determines conviction. Whether a driver is impaired is determined on a case-by-case basis and at the discretion of the prosecutor.
Montana’s drugged driving law is directed at a "Dangerous drug" or "any other drug." A listing of controlled substances regulated by federal law are found at the Drug Enforcement Administration website. It’s not an acceptable defense to a drugged driving charge to claim that the driver is legally entitled to use the controlled substance (Section 61-8-401(2)).
A driver arrested for drugged driving in Montana while be charged with driving under the influence and subject to DUI penalties. A conviction for drugged driving will be considered as a prior offense for purposes of calculating punishment regardless of whether a subsequent offense is due to alcohol or drugs. Read more about Montana’s DUI laws.
Yes, there is an implied consent rule for blood, saliva, and urine testing. The refusal to take the test can be admitted into evidence against the driver.