Field sobriety testing is not always reliable
When Tennessee police officers suspect that a motorist is driving while under the influence of drugs or alcohol, they often ask them to take field sobriety tests. If drivers perform poorly in these tests, the officers may take them into custody on drunk driving charges or ask them to submit to breath or blood tests to determine their blood alcohol levels.
Police conduct field sobriety tests to determine whether or not probable cause exists to take a motorist into custody on drunk driving charges. There are three parts to a standard field sobriety test, which have been endorsed by the National Highway Traffic and Safety Administration, and they are designed to measure a driver’s balance, awareness and coordination. Officers also sometimes request a driver to perform nonstandardized tests. Drivers may be asked to stand on one leg, follow a moving object with their eyes and walk in a straight line before turning.
During the horizontal gaze nystagmus exercise, police officers look for exaggerated eye movements and jerking, and the walk-and-turn test is supposed to gauge how well drivers are able to follow instructions and perform basic tasks. Impairment is indicated during the one-leg stand test when motorists are unable to balance or hop from foot to foot.
Experienced criminal defense attorneys will study videos of the field sobriety tests closely when field sobriety tests have been conducted. Police officers sometimes ask suspected drunk drivers to count or recite the alphabet backwards or touch their noses after closing their eyes, and these techniques have not been endorsed by NHTSA or subjected to rigorous scientific testing Attorneys may also question the validity of sobriety testing on motorists who are overweight, over the age of 50 or suffer from certain medical conditions.