We won a big case last week. Our client was involved in a traffic accident that involved a fatality. Although the accident was not his fault, the government charged him with driving after consuming alcohol, and his driver’s license conditions restricted him from consuming any amount of alcohol while driving. The state’s evidence consisted of two separate breath tests on two different machines.
We held a hearing where our firm cross-examined officers who were on the scene and presented expert testimony. The Court dismissed our client’s criminal case, but the holding is even more critical. The judge ruled that so-called preliminary breath tests (PBTs) are foundationally unreliable for results under .08. In other words, because the tests lack the most fundamental scientific basis, they are inadmissible as evidence.
Why does that matter if the legal limit is .08 or more?
In Minnesota, PBTs use electrochemical fuel cell technology to measure alcohol in a person’s breath. While it’s well-known that police use PBTs as a roadside test to gather evidence to support the arrest of drivers for DWI to show alcohol concentrations of 0.08 or more, it is also used in many legal and administrative contexts for concentrations below 0.08, where lower amounts can have legal consequences.
For example, in Minnesota, fuel cell technology is used for detecting breath alcohol levels below 0.08:
- Purpose: Required for drivers whose licenses are revoked due to DWI offenses.
- Threshold: A “positive” alcohol reading can be as low as 0.02.
- Consequences of a Measurement .02 or greater:
- Lockouts of the vehicle prevent it from starting;
- Extension of the interlock period, potentially adding thousands of dollars in expenses and additional years on the program;
- Possible cancellation of driving privileges
[Note: we prevailed in similar interlock cases where we convinced judges that these devices are not properly calibrated and are affected by substances on drivers’ breath other than ethyl alcohol. You can find that here: ]
- Legal Limit: 0.04 alcohol concentration while operating a commercial motor vehicle.
- Consequences: Administrative disqualification of CDL, even if driving a non-commercial vehicle, can occur if testing positive at or above 0.04.
- Zero Tolerance Law: It is illegal for an underage driver to have any measurable amount of alcohol in their system.
- Threshold: Effectively 0.00—any detectable alcohol results in administrative license sanctions.
- Penalty: Loss of driving privileges, even if the result is well below 0.08.
- Standard: Like CDL holders, the alcohol limit is 0.04 while operating a school bus.
- Detection of any alcohol under 0.04 could still result in discipline or disqualification under employment policies.
- Workplace, Pretrial Monitoring, and Probation
- Context: Probation, pretrial release, or employment monitoring for alcohol abstinence.
- Threshold: Any positive reading, even below 0.08, can trigger violations.
- Devices Used: Often the same fuel cell-based handhelds or interlock units.
Summary:
Minnesota uses fuel cell technology extensively in both criminal and administrative settings, even where no actual DWI crime is charged. The mere presence of alcohol can have serious consequences, especially for CDL holders, underage drivers, repeat offenders, and those under special restrictions.
💡 Practice Tip for Defense Lawyers: Challenge the scientific reliability of these readings, especially at low levels, and whether proper calibration and observation protocols were followed, especially in light of recent Minnesota rulings.
