During a drunk driving investigation, before an officer makes the decision whether or not to arrest a driver, the officer often requests that the driver submit to field sobriety tests. Standardized Field Sobriety Tests (SFSTs) include the One-Legged Stand, the Walk-and-Turn, and the Horizontal Gaze Nystagmus. Such tests are used by the officer to determine whether or not there is probable cause to arrest the driver and require the driver to submit to a chemical test to determine the blood alcohol concentration of the driver. While the Implied Consent Law does allow an officer to mandate that a driver submits to a blood, breath, or urine test to determine blood alcohol level or face a civil suspension of Pennsylvania driving privileges for refusing the test, an officer cannot force a person to complete field sobriety tests.
I know that drivers sometimes question an officer during a DUI stop about whether or not the driver must perform such tests. The officer's responses often vary, but many officers will not simply tell the driver that they do not have to perform the tests. Instead, the officers have told the driver that they would be arrested if tests were not completed, and other officers tell the driver that there is no reason to forgo the tests if the driver is not drunk. The truthful and simple answer is that a driver is not required to complete the sobriety tests, and there is no punishment for failing to complete them.
If a person refuses to submit to sobriety testing, it does not mean that an cannot arrest the driver. An officer may still believe that sufficient probable cause of drunk driving is present to arrest the driver, but the probable cause is obviously based upon some other evidence aside from field sobriety testing.