Irregular driving (zigzagging, driving off the lane markings, etc.)
Field sobriety tests (also known as "FSTs") are commonly employed by officers to uncover a drunk driver. The tests are designed to evaluate a subject's balance, coordination, and the ability to multi-task. The tests vary from the walk and turn to horizontal gaze nystagmus, which scores ability of a person’s eyes to follow an object like a pen from side to side.
These tests were designed to be a good evaluation of a person's sobriety but they can be difficult for a sober person to pass. For one passing is a subjective conclusion for the officer to decide. Also, scientific studies have noticed problems with the accuracy of field tests and have challenged them repeatedly. Last but not least they are not even legally required. It is within your rights to decline to take them and receive no adverse legal consequences except for maybe angering the officer.
After numerous studies sponsored by the National Highway Traffic Safety Administration they have concluded that only three of all the FTSs are effective in detecting a drunk driver. These three are: nystagmus, one-leg-stand, and walk and turn. That means every other FTSs is defective. In mind of these studies law enforcement agencies nationwide have been adopting the recommended "standardized" battery of three tests. However California law enforcements have ignored these results and continue to use whatever tests they prefer.
Precision of Field Sobriety Tests
Contains information on the scientific research on the accuracy of FTSs, and the possibility of federal standards.
Horizontal Gaze Nystagmus
Information on the misuse of the nystagmus, or “eye test”, by officers due to their lack of experience--as cross-examination by a noted San Francisco DUI lawyer demonstrates (see " The Best DUI Lawyers" ").
Field Sobriety Tests
The three "standardized" FTSs as noted by the National Highway Traffic Saftey Administration.
