Ask the DUI Expert: When Does Law Enforcement Administer the Blood Test Instead of the Breathalyzer Test?


September 10, 2014

This week, we ask Officer William Pelarenos: When does law enforcement administer the blood test instead of the breathalyzer test?

Officer Pelarenos: In every State, Standardized Field Sobriety Tests are conducted in accordance with the National Highway Transportation Safety Administration’s (NHTSA) standards. But DUI laws vary from state to state, and police policies vary with each police dept.

Blood tests are usually requested as a result of a traffic crash, especially those involving personal injury or death. Blood and urine tests are also taken for drivers who are driving under the influence of drugs. Of course, the Officer has the right to administer an evidentiary breath test and then ask the driver to submit to blood and urine tests, no matter what type of DUI investigation is being conducted.

The majority of DUI arrests usually just use the breathalyzer test. 


Got a DUI question for Officer Pelarenos? Ask him at



  • My answers to DUI Comments: Can U be forced to take a blood test? Yes, the Police can take a non-consensual blood draw on a DUI arrest. The U.S. Supreme Court ruled in a case Missouri vs. McNeely that Police Officers are required to obtain a search warrant prior to a forced blood draw. Recently, South Dakota had DUI cases that took forced blood draws without a warrant, even after the Supreme Court Ruling because of that State’s Implied Consent law. Be aware that Laws & Police procedures vary from State to State. Question: Accuracy of BACtrack with waiting 20 mins. before test- You need to wait the 20 minutes to eliminate any residual mouth alcohol. I conducted several tests with the BACtrack S80 & I made sure that I waited 20 mins. prior to testing & in my opinion BACtrack was incredibly accurate. Wait the 20 mins. then test. Final question- Should you refuse a breath test and wait for a blood test. A Police Officer can ask for all three tests, Breath,Blood & Urine, a refusal increases the time that your driving privileges will be suspended. An experienced DUI attorney would probably tell you to refuse all testing. In my opinion, use your BACtrack and if you see it’s a low BAC level (.05 & below), then comply with all the tests. Unfortunately, there are people who only had one or two drinks, are stopped by Police and refuse everything, so what happens? DUI arrest. Avoid this dilemma by knowing your BAC and you are in going to be in good shape. Good luck and stay safe.

    William Pelarenos on

  • can u be forced to take a blood test?

    theresa on

  • can one rely on the accuracy of the BACtrack reading with waiting 20 minutes before a test?

    Eugene ONeill on

  • I’ve been told to always refuse a breath test and wait for a blood test. What are your thoughts?

    Mike on

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