One issue that comes up in DUI cases concerns the admissibility of PBT tests.  Generally speaking, in DUI cases the results of a PBT test are not admissible.  However, sometimes the PBT test might help the defense.  In those instances, is the PBT admissible under Pennsylvania law?  Defending DUI casesThe portion of the Vehicle Code dealing with chemical testing to determine the alcoholic content of blood provides in pertinent part:

(k) Pre-arrest breath test authorized. — A police officer, having reasonable suspicion to believe a person is driving or in actual physical control of the movement of a motor vehicle while under the influence of alcohol, may require that person prior to arrest to submit to a preliminary breath test on a device approved by the Department of Health for this purpose. The sole purpose of this preliminary breath test is to assist the officer in determining whether or not the person should be placed under arrest.

While the actual results of a PBT are inadmissible, the circumstance surrounding the administration of a PBT in this case constitutes exculpatory evidence which should have been deemed admissible. Admissibility of testimony regarding whether a PBT produced sufficient evidence to arrest a person for driving under the influence does not violate the purpose behind the rule which excludes the results of a PBT. As the Court has explained, the purpose of the rule excluding the use of a PBT test from evidence at a criminal trial is because the results of a PBT test are not sufficiently reliable to show the amount of alcohol consumed. Arguably PBT results did not attempt to introduce the results of the PBT at trial, but rather the officer’s determination that the results of a field sobriety test were insufficient to arrest Appellant for driving under the influence. DUI law after Birchfield  Importantly, the determination of probable cause to arrest a suspect is the exact purpose set forth in 75 Pa.C.S. §1547 for the use of a PBT. Thus, a defendant should be permitted to attempt to elicit testimony from the officer that he did not charge Appellant with driving under the influence after administering a field sobriety test. Such testimony constituted exculpatory evidence, the exclusion of which prejudiced Appellant by not allowing him a full and fair defense.