If you are driving in Pennsylvania and are suspected of driving under the influence of alcohol, youmay be asked to submit to a breath test or a blood test to determine if there is any alcohol in your system and, if so, what amount of alcohol is detected. However, prior to that, you may be asked to submit to field sobriety tests. These tests are not used to identify whether or not you are actually intoxicated. Instead these tests are used by officers to provide enough support that backs their decision to place you under arrest for suspected drunk driving.
As explained by FieldSobrietyTests.org, there are three different tests that the National Highway Traffic Safety Administration has approved for use in these situations. None of these tests are actually stated to be accurate in all cases. Of the three tests, the one with the highest rate of accuracy is the horizontal gaze nystagmus test which measures an involuntary jerking of your eye. This test is said to be accurate 77 percent of the time.
The walk-and-turn test has an accuracy rate of 68 percent while the one-leg stand test has an accuracy rate of 65 percent. If you are asked to take all three tests, the accuracy rate of the combination is said to be 82 percent. This still leaves a relatively high margin of error.
This information is not intended to provide legal advice but is instead meant to help Pennsylvania residents understand the potential inaccuracies associated with field sobriety tests used for drunk driving investigations by law enforcement officials.