Common Defenses to DUI Charges in Montana

Common Defenses to DUI Charges in Montana

By Colin J. Delli Bovi

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DUI

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Last Modified on Mar 13, 2026

A DUI is a serious offense that can carry life-altering consequences. Driving under the influence is a crime in all 50 states, but the DUI laws in Montana are particularly strict and have recently been reformed with even harsher penalties. However, there are some common defenses to DUI charges in Montana that a skilled DUI attorney in Montana may be able to employ to reduce or dismiss charges.

Breathalyzer and Field Sobriety Test Inaccuracy

Testing the breath for alcohol with a breathalyzer can be inaccurate in some scenarios. The test determines the amount of alcohol particles in the lungs from deep breaths, providing a measurement of the alcohol level in the bloodstream. While this test is often considered the standard for determining DUIs, there are cases where it can administer invalid results.

Like any electronic device, breathalyzers are not fault-proof. A 2025 report found that “mouth alcohol” contamination (alcohol still in the mouth, not deep lung breath) can cause breathalyzers to falsely elevate the blood alcohol content (BAC) reading. This can be caused by burping, hiccuping, vomiting, or conditions like acid reflux and Gastroesophageal Reflux Disease (GERD).

This is extremely harmful to those charged with a DUI if it was due to an uncontrollable condition. A DUI lawyer will be familiar with proper breathalyzer procedure, allowing them to investigate whether or not the BAC taken at the time of arrest should be admissible in court.

Field sobriety tests (FST) can also yield inconclusive or unreliable findings. In a 2023 clinical trial regarding cannabis impairment, it was found that nearly 50% of the sober people given an FST were considered impaired by officers.

This demonstrates that FSTs are not always suitable for determining if a driver is intoxicated. When you hire a DUI lawyer, they may be able to collect relevant evidence to argue that the test was administered incorrectly.

Illegal Stops

To stop a vehicle for a DUI, an officer must have reasonable suspicion that the driver is actually under the influence. DUI checkpoints or sobriety checkpoints are illegal in Montana. If the driver wasn’t swerving, speeding, or otherwise showing signs of impaired driving, all evidence collected from the vehicle stop may be dismissed.

Denied or Violated Constitutional Rights

The Fourth, Fifth, and Sixth Amendments are the three most commonly violated statutes during a DUI arrest:

1. The Fourth Amendment is designed to protect citizens against unlawful search and seizure by the government. If an officer did not have reasonable suspicion to pull someone over, they would be directly violating that person’s Fourth Amendment rights. This is also applicable to illegal searches performed on vehicles without probable cause during a DUI arrest, or arrests made without sufficient proof of intoxication.
2. The Fifth Amendment provides several legal protections. For a DUI, the most applicable is the right against self-incrimination, which is the basis for Miranda rights. If someone invokes their right to be silent during a DUI arrest and is still questioned or interrogated, this is a violation of their Fifth Amendment rights.
3. The Sixth Amendment requires that those accused of crimes be provided with legal counsel. If someone is denied the ability to speak to an attorney during a DUI arrest, their Sixth Amendment rights have been violated.

If you believe your legal rights were violated during a DUI arrest in Montana, don’t hesitate to get the justice you deserve with an attorney from Delli Bovi, Martin, & Reed, LLC.

Why Should I Hire a DUI Lawyer in Montana?

Several Montana counties have unique requirements for those convicted of DUIs. A skilled Montana DUI lawyer will be familiar with the local courts’ procedures and preferences, helping them to determine the defense suitable for your unique case.

For example, the Missoula Municipal Court requires the use of SCRAM Continuous Alcohol Monitoring (SCRAM CAM) ankle bracelets in extreme DUI cases. SCRAM CAMs test the user’s sweat for alcohol content every 30 minutes on a 24/7 schedule.

Delli Bovi, Martin, & Reed, LLC, for Your Montana DUI

At Delli Bovi, Martin, & Reed, LLC, we know a DUI is a serious charge that needs to be handled with care. Our team has over 40 years of combined experience, resolving over 1,000 cases for our clients. We practice throughout the entirety of Montana, making us familiar with the courts from Beaverhead to Custer County.

FAQs

What Is the New DUI Law in Montana?

The new DUI law in Montana is Bobby’s Law, which was introduced to the Montana legislature in 2025. The new mandatory minimum prison sentence for DUI manslaughter is 3 years (up to 30) if the driver’s BAC was 0.16% or higher. The high BAC in these cases causes it to be considered aggravated vehicular homicide, preventing DUI loopholes from being exploited.

What Makes a DUI Case Weak?

There are often several aspects that contribute to making a DUI case weak. Improperly obtained evidence, lack of evidence, and contradictory evidence can all cause a DUI charge to be dismissed. Improperly administered FSTs and faulty breathalyzers are examples of insufficient evidence that can weaken DUI cases. A DUI lawyer can determine what evidence should and should not be admissible in your case.

What Are Mitigating Factors in a DUI Case?

Mitigating factors in a DUI case suggest that the DUI was either not an extreme case or clearly out of character for the accused party. Examples of mitigating factors in a DUI case include no criminal record, low BAC, cooperation, and rehabilitation. Mitigating factors can diminish or even dismiss DUI charges in some cases.

Is Montana Tough on DUIs?

Montana is not considered one of the states that is toughest on DUI offenses. While the state may not have the toughest DUI laws, there are still significant consequences for driving under the influence, especially with the introduction of Bobby’s Law. Cases with aggravating factors, such as prior convictions, can potentially result in harsh penalties.

Contact Delli Bovi, Martin, & Reed, LLC, Today

Based in Helena, our office consists of knowledgeable attorneys well-versed in Montana’s complex DUI laws. If you or someone you know has been charged with a DUI, don’t wait to get the representation who will advocate for you. Contact the team at Delli Bovi, Martin, & Reed, LLC today for your DUI case needs.