Field sobriety tests are often the backbone of evidence used against alleged drunk drivers for conviction. These tests are designed to provide law enforcement officers with enough information to determine whether or not a motorist is too impaired to safely operate a motor vehicle. In Arizona, motorists are not legally required to undergo any type of field sobriety test, as it requires them to provide potentially incriminating evidence to police officers.
There are five commonly used field sobriety tests in Arizona, which are also generally used throughout the nation as a whole. However, only three of these five tests are standardized, approved and recommended for officer use by the National Highway Transportation Safety Administration. FieldSobrietyTests.org indicates that the three approved tests include the Horizontal Gaze Nystagmus, the Walk-and-Turn, and the One-Leg Stand. The finger-to-nose test and the finger counting tests are less commonly used and are not standardized.
According to the NHTSA, when these approved tests are performed and scored properly, officers can accurately determine inebriation in only 88 percent of cases for the HGN, 79 percent of cases tested using WAT and 83 percent of cases using the OLS. When combined, their accuracy can reach 91 percent. However, the NHTSA reiterates that the accuracy of these tests is contingent upon administering law enforcement officers following the correct, standardized procedures for each test. When officers are not properly trained in these procedures, mistakes can be made that lead to a false DUI charge.
In many cases, people are falsely accused of drunk driving after taking these tests due to medical reasons. The tests do not account for the potential for health conditions that affect motor skills and the normal function of the body. Those with hip or knee replacements, serious back injuries or obesity can all receive a false positive. For these reasons, many motorists may choose to forgo field sobriety tests and avoid being improperly scored and charged.