As a State College criminal defense attorney, I am frequently asked by friends, family, and DUI clients, whether or not a person suspected of driving under the influence should attempt to perform field sobriety tests. Actually, the first question is whether or not a person is required to perform field sobriety tests, and the second question is whether or not a person should attempt such tests. The standard field sobriety tests that are used in Centre County DUI cases are the one-legged stand, the walk-and-turn, and the horizontal gaze nystagmus (HGN). Some people also consider the preliminary or portable breath test (PBT) as being another sobriety test that is routinely used in a DUI investigation.
Field Sobriety Tests in a DUI Investigation are Not Mandatory
With regard to the first question, the answer is no. A person suspected of driving under the influence is not required to perform field sobriety tests. While you are not required to submit to sobriety testing, the police officer is not required to inform the DUI suspect that the tests are not mandatory. Not only do the police not inform you that the tests are voluntary, the police often tell the person that the officer "needs" the DUI suspect to perform the tests. The police encourage the DUI suspect to attempt the tests as an investigative tool. A failure to successfully complete the tests adds to the officer's probable cause that is needed to arrest the suspect and then requires the person to submit to blood alcohol testing.
While successful completion of the tests make it less likely that the DUI suspect will be arrested, successful completion does not guarantee that the person will be released. To the contrary, if the officer still believes that he had probable cause to think that the suspect was driving under the influence, the officer can arrest the suspect and require him to submit to a blood alcohol concentration test. Successful completion of the tests will give the DUI suspect a better argument in the future to argue that the officer did not have probable cause to arrest and thereby seek suppression of the blood alcohol evidence.
Since successful completion of the DUI field sobriety tests do not guarantee that DUI charges will not be filed, there is practically no benefit to attempting to complete the tests. Centre County DUI suspects should not submit to field sobriety tests or a preliminary breath test (PBT).
What Happens If I Refuse Sobriety Tests or the Breath Test
Nothing. As a person is not legally required to perform field sobriety tests or submit to the preliminary breath test, there is no punishment for not submitting to such DUI tests. I need to distinguish between the breath test that is administered during the DUI investigation at the scene and a breath test that may be administered after the person is arrested. Officers are permitted to request that a DUI suspect submits to a preliminary breath test at the scene, and the DUI suspect is permitted to refuse this test without ramifications. However, if a suspect is arrested for suspicion of DUI, then the officer can require the person to submit to a blood alcohol concentration test, and the officer is required to inform the DUI suspect that a failure to submit to this post-arrest testing will result in a suspension of driving privileges as well as increased criminal penalties if the person is convicted of DUI. In Centre County, the post-arrest testing is done via the withdrawal of blood, normally at the Mount Nittany Medical Center. In some counties in Pennsylvania, the post-arrest blood alcohol concentration test is done via a breath test, but it is a much more precise breath test than the PBT. Due to its relative inaccuracy, an alcohol level reading from a PBT is not admissible in court in a DUI case.
To conclude and summarize, I do not recommend that DUI suspects attempt to perform field sobriety tests or submit to the preliminary breath test because they are not legally required to do so, there is no penalty for not submitting to such DUI tests, and because a person can still be arrested even if they successfully complete field sobriety tests.