Preliminary Breath Test vs. Breathalyzer Test

Maryland's Alcohol Education Program in DUIDWI CasesWhen charged with a DUI or a DWI, clients are often confused about why they’ve been asked by a cop to take one “breathalyzer” test on the side of the road and another at the police station. While they may seem similar, these two breath tests are different and serve different purposes for law enforcement.


A breath alcohol test that is administered on the side of the road is known as a preliminary breath test (PBT). During a traffic stop, a police officer who has reasonable grounds to believe that you may be driving under the influence may request that you submit to a preliminary breath test. The police officer will use a handheld device to measure your breath alcohol content (BrAC). The police officer cannot use the results of the PBT to establish that there is probable cause to place you under arrest for DUI or DWI. If you are arrested for a DUI or DWI you will be taken down to the police station where a Breathalyzer test will be administered.


A chemical breath test, also known as a Breathalyzer, is administered at the police station after you are placed under arrest. A Breathalyzer is conducted on a much larger machine and is considered more reliable than a PBT. Before you take the Breathalyzer, the police are required to read you certain rights prior to asking you to blow into the machine. Police officers who administer Breathalyzer tests receive specialized training on how to properly conduct the tests.


The PBT and Breathalyzer test in Maryland both measure a driver’s BrAC, but the results of the test (and their refusals) are very different. If you are asked to take a PBT, you have the right to refuse to take the test. Police officers won’t always inform you of this fact, but they should. Not taking the PBT doesn’t mean you won’t be arrested. In contrast, under Maryland’s “implied consent” law, you can face an administrative penalty for refusing to take a Breathalyzer test at the police station. The penalty for refusing to take a breath test is the 270-day suspension of your driver’s license on the first offense and one year for a second offense. In addition, the results of a PBT cannot be used by a prosecutor as evidence of your BrAC. On the other hand, the Breathalyzer evidence of your BrAC can be used in court.


If you’ve been arrested for a DUI or DWI it’s essential to make sure you have an attorney who is very experienced in Maryland DUI/DWI law to help you get the best outcome in your case. Contact us at Alpert Schreyer, LLC or call us at 301-321-7277.

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