There are three tests that are generally used to attempt to gauge whether a driver may be impaired by alcohol or other substances. These three tests are the ones most widely accepted by the criminal justice system, and they are generally allowed to be submitted as evidence, though every case is different. If you have been charged because of an allegedly failed sobriety test, how do you effectively challenge the results in a Tennessee court?
The three main tests that are most widely accepted include the walk-and-turn test, the one-legged stand test and the more scientific HGN or Horizontal Gaze Nystagmus test. The basis of the first two tests is the presumption that sober drivers can perform more than one task at a time, while one who is allegedly impaired would be unable to do so. However, there are many reasons why one may do poorly on any test while under duress.
The third test requires the officer administering the test to be trained to recognize whether a driver's eye movements are consistent with impairment. However, any driver may fail any one of the three tests for reasons other than impairment. Disability, illness or even adverse weather conditions could cause a driver to fail to perform the tests as expected.
These tests could easily be administered under questionable circumstances and by officers poorly trained to oversee them. Furthermore, there are many individuals who may not be able to perform more than one task at a time even without being under the influence of any substances. Any Tennessee driver who has been charged after it has been alleged that he or she has a failed sobriety test does have recourse to challenge any and all aspects of the case that has been filed, including the qualifications of the officer administering the tests, as well as the tests themselves and the conditions under which one was stopped in the first place. In addition, every driver is entitled to the presumption of innocence while seeking to clear their name of any wrongdoing.
Source: duijusticelink.aaa.com, "Standard Field Sobriety Test", Nov. 14, 2014