Blood Test Evidence Issues

Estimated reading time: 4 minutes

Blood test evidence is common in Minnesota DWI cases. But it can come up in other cases as well. You can benefit from a DWI Defense Attorney familiar with blood test issues.

Here is a concise guide to some of the important issues in blood testing.

Blood Test vs. Urine & Breath

After a DUI arrest in Minnesota, the police officer will request a bodily fluid or gas sample for chemical testing. Usually, the police officer suspects the person may be under the influence of alcohol. 

But sometimes they suspect the presence of another drug. Blood, urine or breath can test positive for alcohol. Only a blood plasma test can show Delta-9 THC levels for use as evidence, for example. For more on marijuana & THC blood tests:

Marijuana DUI Myth vs. Science.

The police officer in Minnesota makes the initial choice of blood, urine or breath. Breath testing is the cheapest and fastest, since it does not require sample testing in a lab. 

And the law requires a search warrant, prior to the urine or blood sample.

In Minnesota, the law does not allow a police officer to frame a person as a “refusal” if the person refuses blood, unless the person also refuses to provide a urine sample. And the reverse is also true. An officer cannot frame a person for refusal, unless the officer first offers to draw a blood sample after a urine sample refusal. 

As a result, the person under arrest for DUI can effectively choose a blood test or a urine test, if they know about this “alternative test” right. But if the person refuses a breath test, that’s it.

Additional Test right

Regardless of which type of sample the driver provides (blood, breath or urine), if the driver does provide police with a sample for testing, then the driver has the right to an “additional test.” The Constitution includes a right to potentially exculpatory evidence – evidence of innocence.

And a Minnesota Statute reinforces that right in DUI cases, creating a statutory right to an “Additional Test” after providing police with a sample. As a practical matter this additional test can be either a blood test or a urine test. Minnesota courts have ruled that upon request, police must provide access to a phone for the arrested person to arrange an additional test, and must allow another person to see the arrested person to collect a blood or urine sample. 

If police interfere with the additional testing right, the government will not be allowed to use the chemical test they took earlier. Some police instead respond to a request for an additional test, by immediately releasing the person from custody, often to the care of another sober adult. 

Should this happen, the person facing a possible DWI charge should go straight to an ER or elsewhere to get a blood sample drawn for testing.

Blood Test Issues

Many issues can make a blood test unreliable, inaccurate and inadmissible as evidence.

1. Preservative in vacuum tubes
2. BCA blood kit vs. Hospital blood kit
3. Blood draw alcohol contamination
4. Qualifications of blood drawer
5. Chain of custody
6. Blood type or DNA mismatch
7. Salting and fill level
8. Forced draw (Schmerber) issues
9. Search warrant problems
10. Lab or lab tech issues

As you can see, a blood test can have many problems that can make them unreliable, inaccurate and inadmissible in court. So, having an experienced DUI lawyer help with a blood test is important, and can make the difference. The witnesses for the government in blood test cases typically include:

• police officers
• person who drew the blood sample
• others in the chain of sustody
• lab tech

And the defense attorney can cross-examine or question them, to reveal facts favorable to the defense. 

Expert Witnesses

Most witnesses are “fact witnesses.” But some are “expert witnesses.” And expert witnesses are can testify to their opinions about the meaning of certain facts, if their expert opinion would help the jury. Both sides can bring in expert witnesses. But the cost of an expert witness’s work and time can be significant, and a burden to the defendant.

Even so, in some cases we can see that the defense may need an expert witness to help the jury understand just why the blood test is not reliable or accurate.

Question? Call Attorney Thomas Gallagher, 612 333-1500

Need help with a blood test in a Minnesota DUI case? Call DUI Attorney Thomas Gallagher for an assist.

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