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3 Ways to Challenge a DUI Blood Test

By Tanya Roth, Esq. | Last updated on

So you've been pulled over for drunken driving and now want to know if you can challenge your blood alcohol test. You've been hearing that these DUI tests can be challenged, particularly the breath tests.

You're right. First of all, the legitimacy of breath tests and their accuracy has come under scrutiny. In Pennsylvania, for example, the calibration of certain Intoxilyzer machines was found to give results that were slightly off. In a state where DUI penalties hinge on the amount of intoxication, that's a huge deal.

Of course, the same result wasn't reached in Minnesota, where the Intoxilyzer machine's results were ruled valid, despite pushback from DUI lawyers, the Minneapolis Star-Tribune reports.

So what about challenging a DUI blood test?

As with alcohol breath tests, there are many ways to challenge a blood test. Some can be more successful than others.

Here are three ways it can potentially be done:

  • Challenge the person administering the blood draw. You have a good case against the reliability of your DUI blood test if the person wasn't properly qualified to perform the blood draw. Or sometimes, there may simply be issues with the technician, even if she appears qualified -- remember the case of Annie Dookhan, the lab technician who was allegedly faking her results in Massachusetts?

  • The chain of custody argument. If you follow the chain of custody -- i.e., who had possession and control over the blood sample -- you might find some troubling gaps. The blood sample is not supposed to be tampered with, so authorities are required to keep track of who had it in their custody, and when. Any breaks in the chain of custody could lead to the blood test being tossed out of court.

  • Challenging the calibration of equipment. Taking a page from the Intoxilyzer challenge, an argument can be raised on improper calibration of the machines and equipment used in the blood draw.

Of course, these are only three arguments that can potentially be raised to challenge a blood alcohol test. An experienced DUI lawyer, especially one who's challenged DUI blood tests in the past, may come up with a different challenge for your specific situation.

Then again, you have to ask yourself if it's worth your time to challenge the test's results. As some states have more lenient penalties for drunken driving than others, that's another issue you will want to discuss with an attorney.

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