.08% BAC is the “legal limit” or per se under the influence level

In Montana, you may be arrested and charged for driving under the influence if you are impaired and/or your blood alcohol content (BAC) is over .08%.  You can be charged with DUI under 61-8-401 MCA or with DUI per se under 61-8-406 MCA.  If tests reveal the presence of drugs in your system in a blood test, you may be charged with a DUI-Drugs offense.  If you drive a commercial vehicle, the BAC limit is .04%.