When a driver has been stopped at a sobriety check point or by an officer on patrol, there are a series of procedures and tests an officer should conduct in determining if the driver is impaired before making a DUI arrest. The officer will engage the driver in conversation to determine if the driver had been drinking, then proceed to look for apparent clues like slurred speech, alcohol odor, face and eye color (checking for redness of the eyes or flushed face). If the officer has “reasonable suspicion” that the driver might be impaired, the officer will typically request the driver to step out of the car to perform a series of field sobriety tests (SFSTs).
There are many SFSTs that police can conduct on someone, such as the finger-to-nose, finger-to-thumb, hand pat, and alphabet recitation assessments, among others; however, the accuracy of these tests continues to be scientifically challenged. The National Highway Traffic Safety Administration recommends a 3-test battery of standardized field sobriety tests because studies have indicated that other field tests were unreliable. The three standardized tests are the horizontal gaze nystagmus test (follow the pen with the eyes), the walk-and-turn test (heel-to-toe in a straight line) and the one-leg stand test. These tests were designed to test balance, coordination, and divided attention. It is important to remember that these tests are entirely subjective and can even be difficult for a sober person to pass.
Drivers can refrain from taking these sobriety field tests since they are not legally required, and there is no penalty for refusal of these tests. Many have argued the only reason these tests are conducted is to give the officer justification to require a chemical test such as a blood, breath, or urine test. The main defense for refusing to comply with the SFSTs or refusing to take a chemical test is that the officer did not have “probable cause.”
If you have taken one of these field tests, there are many possible defenses available for DUI charges. Police have been known to make mistakes during a DUI arrest. For example, a police officer’s training manual on SFSTs indicates that if the driver moves his head during the “follow the pen with the eyes” test, the officer should use a flashlight as a chin rest for the suspect. Also, the manual states that the walk-and-turn test requires a line that the suspect can visibly see; in the one-leg stand test, an officer should not test people who are 50 pounds overweight or are physically impaired.
Another possible defense in a DWI case is the reliability of the breath testing machine itself. The machine can be flawed and readings can vary up to 50% from the actual breath content. If requested, the police will have to provide the test records of the breath test, the machine maintenance records, and qualifications of the breath test operator.
The three standardized sobriety tests were intended to predict a BAC of .10 or above. Since the legal limit has tightened to .08, there is almost no weight that a judge could place on these tests for someone with a BAC of .08 or .09.