One of the best-known field sobriety tests, the finger to nose field sobriety test is somewhat outdated. Once one of the most commonly relied upon tests for determining the impairment of a driver, it is not recognized by the National Highway Transportation Safety Administration (NHTSA) as one of the top three most reliable field sobriety tests.
Non-standardized tests, like the finger to nose test, are only still used in certain states. Many states have outlawed the practice of any but the NHTSA standardized tests, because the others are considered far too subjective.
Part of the problem with the finger to the nose test is that sober individuals can fail it. The subject is asked to stand with both feet together and with the arms perpendicular to the body (straight out at the sides).
Then, the individual must, with both eyes closed, reach one hand at a time to touch the nose with the pointer finger. Some officers may ask the subject to bring the finger as close to the nose as possible without touching it while others may ask for alternating hands.
Non-standardized testing means that there is no set protocol for the administration of the tests. Therefore the officer has more leeway to determine what to ask the subject to do. Obviously, this affects the reliability and validity of the test. Officers may make an arrest based on the subject missing the nose, swaying, or making a mistake in following the directions.