A field sobriety test is a set of three physical tests a police officer may ask you to take if he or she suspects you of driving under the influence. These tests assess coordination, balance, the ability to obey orders and other physiological factors that may signal intoxication.
While these are standard tests, they are not always completely accurate. It is possible to receive a false positive for several reasons.
Field sobriety tests are subjective, relying solely on police officers’ judgment, introducing a variability not usually present in tests not based on opinion. Two officers might interpret the same signs of impairment differently because they are not objective. They may also make errors in administering the tests.
Another factor that may cause you to fail a field sobriety test without taking a sip of alcohol or partaking of any drug is your physical or mental fitness. Certain medical conditions or physical limitations may make it challenging for you to perform specific tasks required during these tests. Issues like inner ear problems, dry eye, back pain or even anxiety can affect your balance and coordination, creating a misleading impression of intoxication. Even stress or exhaustion can cause you to make a mistake during part of the test.
Environmental conditions, such as poor lighting, uneven terrain or adverse weather, can impact your ability to perform well. Slippery roads or windy weather might cause you to stumble or fall, making you seem unsteady, which the officer may interpret as a sign of intoxication.
While police officers receive training for administering field sobriety tests, there is currently no way to eliminate all errors. Besides older studies showing that they are not completely accurate when testing other forms of intoxication, a more recent study also shows that it is not an accurate measure of cannabis impairment. A false positive for intoxication can act as evidence against you in court, so it is important to remember you have this right and consider your overall condition before submitting to a field sobriety test.