Field sobriety tests (fsts) are roadside tests used by officers to detect potential impairment.
Officers use potential impairment to develop probable cause to arrest and administer a blood, breath or urine test. Potential impairment/probable cause is not the same thing as beyond reasonable doubt. It is not a police officer’s job to determine if someone is guilty. While fsts may show some form of potential impairment, it is up to the prosecutor to show actual impairment caused by the consumption of alcohol and/or drugs.
Studies have shown that:
- sober people can have difficulty with balance;
- weight can affect the tests;
- age can affect the tests;
- leg problems can affect the tests;
- back problems can affect the tests;
- middle ear problems can affect the tests;
- footwear can affect the tests; and
- roadside conditions can affect the tests.
According to recent research, fsts do not measure impairment of the ability to safely drive a car. Experienced counsel with knowledge of the scientific, procedural, and tactical considerations is essential when combating field sobriety evidence in court.
Horizontal Gaze Nystagmus
The Horizontal Gaze Nystagmus Test measures the movement of the eyes. Nystagmus is the jerking of the eye. Alcohol slows down the eyes’ ability to rapidly track objects and causes eyes to oscillate, or “jerk” before they normally would in a sober person. As a person’s blood alcohol concentration increases, the eyes will “jerk” sooner as they move to the side.
The Horizontal Gaze Nystagmus test is a limited tool. It is designed to be used by an officer to determine whether an individual is a good candidate for blood or breath testing. Unfortunately, the police and prosecution often attempt to use the test result as evidence of impairment. Competent defense counsel should be sought to explain the limits of the nystagmus test.
Attorney Robert A. Butler is a former DUI prosecutor who has participated workshops training officers to be qualified to administer field sobriety tests. Mr. Butler knows the results of these tests can and should be challenged. Robert A. Butler has defended people charged with DUI valley wide including Phoenix, Tempe, Scottsdale, Gilbert, Mesa, and Chandler. Contact us today for a free consultation.