In Montana, according to the Montana Department of Public Health and Human Services, it is illegal for you to operate a vehicle with a blood alcohol concentration level at or above 0.08%. If you are under the age of 21, a law enforcement officer can arrest you for drinking and driving with a BAC level of 0.02% or above.

One way law enforcement can determine your BAC level is by conducting a blood or breath test. According to the Montana Code, if you choose to drive a car on a public road in Montana, you automatically consent to take a blood or breath test if requested by a law enforcement officer during a drunk driving stop.

When law enforcement can administer a test

A law enforcement officer may choose to administer a blood or breath test for DUI  if he or she believes you drove a vehicle on public roads while under the influence of drugs, alcohol or a combination of the two. The officer may also choose to conduct a blood or breath test if you are under the age of 21 and allegedly violated the underage drinking and driving law.

Additionally, a law enforcement officer may request a blood or breath test if you got into an accident that resulted in property damage or serious bodily injury.

What happens when you refuse a test

If you choose to refuse a blood or breath test after a DUI arrest, the arresting officer can immediately seize your driver’s license. The law enforcement officer can take your license for refusing a blood or breath test alone, regardless of whether you are guilty of driving under the influence.

If it is the first time you refuse a test during a DUI arrest, you will lose your license for six months without the option for a restricted license. If it is the second time you refuse a test within five years of the first refusal, you will lose your license for a year, and you cannot obtain a probationary license.