In Minnesota, drivers who refuse a breath alcohol test during a DWI investigation can be charged with the crime of “Refusal to Submit to a Chemical Test.” This can lead to serious consequences: a gross misdemeanor criminal charge, a one-year license revocation, and lifelong stigma that can jeopardize employment, housing, and professional licenses … and that’s for first timers!
But what most people don’t realize is this:
You can be charged with refusal, even when you blow into the machine!
Yes, you read that right. If the machine doesn’t accept your breath sample as “adequate,” the state can charge you with refusal, even if you tried to comply.
What Constitutes “Refusal” Under Minnesota Law?
Under Minn. Stat. § 169A.20, subd. 2, it is a crime to “refuse to submit to a chemical test” under the state’s Implied Consent Law. The Implied Consent Law itself (found in § 169A.51, subd. 5(c)) states that “failure to provide two separate, adequate breath samples in the proper sequence constitutes a refusal.”
But here’s the catch:
Nowhere in the statute does it say what an “adequate” breath sample is. The Legislature left that definition out of both the criminal law and the administrative rules. Instead, it’s buried deep in the DMT (DataMaster Transportable) operator manual—a 147-page technical manual used by police officers that’s not shown to the public. [You can find it here.]
The Machine’s “Acceptance Criteria”: Complex, Unpublished, and Flawed
According to the DMT Operator Manual (Page 21), a breath sample is only accepted if it meets all four of the following conditions:
- A minimum flow rate of 2.87 liters per minute;
- A minimum volume of 1.5 liters per breath sample;
- A stable slope of the breath alcohol curve, determined by tremendously complex calculations not visible to the subject or the operator; and,
- A drop in the flow rate below the 2.87 L/m minimum at the end of the sample.
If any of these criteria aren’t met, the machine deems the sample “inadequate.” You will lose your driver’s license, and prosecutors will charge you with refusal.
But here’s the problem:
- The flow rate and volume sensors on the DMT have never been independently tested by the Minnesota Bureau of Criminal Apprehension (BCA) for accuracy.
- The machine gives no feedback to the driver explaining why the sample was rejected.
- Some of the requirements—like the alcohol curve slope—are based on variables completely outside the driver’s control.
- The only volume testing the BCA performs uses a 3.0-liter syringe with a ±0.15-liter margin of error, making it unreliable for determining the precise 1.5-liter minimum requirement.
- The machine’s internal thresholds and failure criteria are based on unpublished technical standards, not on statutory authority.
Due Process Concerns: How Can You Obey a Law That Doesn’t Explain Itself?
The U.S. and Minnesota Constitutions require that criminal laws provide notice of what conduct is prohibited. A statute must be clear enough so that an average person can understand what’s illegal and modify their behavior accordingly.
But how is a driver supposed to know that:
- Blowing too gently,
- Having low lung capacity,
- Or even just having a fluctuating alcohol curve slope
…will result in a criminal charge?
They can’t.
And the police don’t tell them (heck, most cops don’t fully understand). The machine doesn’t either.
This isn’t just a flaw in procedure, it’s a constitutional violation. When a person is charged with a crime for not meeting secret, unpublished standards that are technical and confusing even for trained officers, the law fails to provide adequate notice. That’s a violation of due process.
The Real-World Consequences
These aren’t just technicalities. We’ve seen clients who:
- Tried their best to blow but were still charged with refusal.
- Had their licenses revoked for a year.
- Lost jobs and careers—including one man who was forced out of his role as a conservation officer.
- Spent thousands of dollars on ignition interlock devices and reinstatement fees—all because of a machine error.
And just last week, a Minnesota district court judge threw out a criminal case based on a preliminary breath test (PBT)—highlighting how fragile and unreliable these tools are. Though the DMT device once featured a fuel cell sensor as a secondary measurement method, the Minnesota BCA disabled the fuel cell in 2012 because it was rejecting too many samples due to interfering substances and was costly to maintain.
This means Minnesota currently relies solely on the infrared analysis method within the DMT—a single method that still has critical limitations and error margins.
There Are Defenses—And We Know How to Use Them
Our lawyers are the only two who reside in Minnesota who are factory-trained DMT operators and supervisors. Additionally, we have studied the full DMT training manual and undergone advanced breath testing training. We understand the flaws in the system, and we know how to hold the state accountable when the law is unfairly applied.
Physical Impossibility: Another Powerful Defense
In many cases, our clients did everything they could to comply with the test, but were physically unable to meet the machine’s demanding technical requirements. We’ve successfully defended clients where the test failed due to equipment issues, such as a poor mouthpiece seal that allowed air to escape, or medical conditions that made it impossible to meet the machine’s flow rate and volume thresholds.
Aging naturally reduces lung capacity. Conditions like COPD, asthma, or prior cancer treatments that cause lung scarring can make it difficult or impossible to deliver a sufficient sample. We’ve also highlighted how certain demographic factors can contribute to physical limitations: women, on average, have smaller lung volumes than men, and studies show that African Americans and Asians tend to have lower average lung capacities than Caucasians.
The law doesn’t account for these differences, and the machine doesn’t either. But the courts should—and in several of our cases, they have.
If you were charged with breath test refusal, don’t give up. You may have a strong defense based on:
- The machine’s failure to accurately determine flow or volume
- Lack of notice of what’s required
- Due process violations stemming from unclear or unpublished standards
- Physical Inability
- Your actual attempt to comply with the test
We’re here to help.
If you or someone you know is facing a breath test refusal charge in Minnesota—either criminally or administratively—contact us, experienced DWI Lawyers in Minnesota. We’ll review your case, analyze the machine data, and fight to ensure your rights are protected. We regularly beat test refusal cases, and we may be able to help you, too.
Don’t let a machine error define your future. Know your rights. And if the system failed, you fight back.
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