In Minnesota DWI cases, prosecutors often rely heavily on blood test results. While these scientific tests seem hard to dispute, drivers have legal options to challenge them.
The state must follow strict rules when gathering and analyzing blood samples. Errors during this process can allow a driver to challenge the reliability of the test or seek to keep the results out of court.
Grounds for challenging a DWI blood test
A successful defense often relies on finding legal, procedural or scientific mistakes in how the state handled the blood sample. Drivers can challenge blood test evidence on several grounds:
- Constitutional violations: Officers must usually obtain a search warrant or get voluntary consent before drawing blood. If police fail to follow these rules, a court may throw out the test results.
- Unauthorized staff: Under Minnesota law, only specific qualified people may draw blood for a DWI test. These include doctors, registered nurses and medical technologists. A blood drawn by an unqualified person can make the sample invalid.
- Chain of custody errors: The state must document who handled the sample from the moment of the draw to the final test. Gaps in these records can raise questions about tampering, mislabeling or contamination.
- Testing equipment flaws: Laboratories use complex tools like gas chromatography to measure blood alcohol levels. If lab workers fail to calibrate these tools or make testing errors, the results may be inaccurate.
- Time limits: Minnesota law generally requires the state to test a driver’s alcohol levels within two hours of driving. If the blood draw occurs after this window, the court may reject the results.
- Right to counsel: Drivers have a limited right to speak with a lawyer before deciding to take a chemical test. If officers deny this right, the court may suppress the test results.
Understanding critical deadlines
A DWI arrest starts two separate legal cases: a criminal charge and a civil license revocation.
In the civil case, the state can revoke a driver’s license before the criminal trial even begins. Under Minnesota law, drivers have 60 days from the notice of revocation to file a petition to challenge the loss of driving privileges. Missing this deadline usually means forfeiting the right to contest the license revocation.
Protecting a driver’s legal rights
A detailed review of the evidence is necessary because blood test defenses depend heavily on the unique facts of each stop and arrest. A Minnesota DWI defense lawyer can review police reports, search warrants and laboratory records to build a strong challenge against the test results.
