The Philadelphia DUI Law Blog

3 Ways to Challenge a DUI Breath or Blood Test

If you are charged with driving drunk, you may want to know some ways to challenge a DUI blood test.

At the time of arrest, a DUI suspect is often asked to submit to a Breathalyzer or some other test to determine the suspect's blood alcohol level. This can include taking a blood sample and analyzing it.

The results of these tests are typically key to proving that you were driving drunk. However, just because some device or lab tech says that your blood alcohol level was above 0.08%, you may still be able to fight the charge in court.

Blood alcohol monitoring devices like Breathalyzers are notorious for their inaccuracy. And even if these devices are working properly, authorities may make other mistakes that can cast doubt on the accuracy of the test results.

Here are three common ways that DUI defendants can potentially challenge DUI breath or blood test results:

  1. Problems with the device. Machines are not infallible. Devices like the Breathalyzer must be properly maintained and calibrated to work properly. If you can show that the police officer did not follow proper protocol in calibrating the device, you may be able to throw out the evidence gathered from the device.

  2. Problems with the person administering the test. If you've ever had blood drawn by a nurse, you know that it is not that easy. This can be an issue in some cases: If your blood wasn't drawn by someone qualified to do so, it may not be reliable enough for the court.

  3. Problems with chain of custody. Assuming the device was working properly and the person administering the test knew what she was doing, your blood test could still be thrown out if there are problems with the chain of custody. Authorities generally have to account for everyone who handled your blood sample. Any gaps in the chain can cast doubt on the reliability of the sample.

If you have charged with a DUI, you may want to contact an experienced attorney to work on your defense.

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