Many Tennessee residents have joked about the fact that they could not walk a straight line or say the alphabet backward even if they were sober. Even though this is often said in jest, the truth of the matter is that it is not far from the truth. Field sobriety tests are often not a reliable indicator of impairment, and many people have been arrested for DUI based on these tests, only to have the charges dismissed later.
Two of the three tests designed by the National Highway Traffic Safety Administration (NHTSA) -- the walk-and-turn test and the one-leg stand -- are heavily affected by a driver's physical condition. Some people are just not that physically coordinated even if they have not been drinking. Even so, some physical factors have been shown to affect whether an individual is able to adequately "pass" field sobriety tests.
Any with back and/or knee problems might not be able to perform the tests. People who are 50 pounds or more overweight have also been shown not to be able to properly perform these tasks, along with anyone over the age of 65. Test results can also be skewed if you are wearing high heels during the test. Of course, taking these types of physical issues into account makes the assumption that an officer has the proper training and is performing the tests in accordance with established procedures.
These tests are used to establish probable cause for an arrest, and if there is a problem with the testing -- either from your end or from the officer's end -- the legal reason for the arrest disappears. Should it be proved that the testing was flawed, the charges against you could be dismissed for lack of probable cause. Therefore, if you are arrested on suspicion of driving under the influence here in Tennessee based on field sobriety tests, you should contact an attorney as soon as possible.