Oregon law enforcement officers cannot just pull drivers over, order them to walk in a straight line, wave a flashlight back in forth in front of their faces, and determine that they are drunk. The Standardized Field Sobriety Tests must be administered in a certain way to be admissible as evidence in court.
According to AAA, the walk-and-turn test is more than just a few steps along a line beside the road. The officer is looking for specific indicators that the driver is impaired:
- Not maintaining balance while the officer gives the instructions
- Starting before the instructions have all been given
- Having to regain balance while walking or putting arms out for balance
- Failing to touch the heel to the toes on each step
- Stepping off the line or taking the wrong number of steps
- Not turning as the officer instructed
Even if the test is administered correctly and the driver does display two or more of these indicators, the likelihood that he or she has a blood alcohol concentration over the legal limit of 0.08 percent is only about 79 percent.
In addition, the officer must have the driver take the one-leg stand test, again looking for very specific indicators. The driver must stand with one foot about six inches in the air and count by ones starting with 1,000. This test should last about 30 seconds, and the driver must not sway, use the arms, hop or put the foot down to keep from losing balance. Any two of these are about 83 percent effective at identifying a driver with a BAC over the limit.
Finally, the officer must understand and administer the horizontal gaze nystagmus test. When tracking a moving object, an inebriated person's eyes will jerk involuntarily. However, people with one of many medical conditions or who take a variety of medications will also have the same reaction.
Any failure on the part of the officer to administer the test correctly could lead to a challenge of the results in court. However, if a driver refuses to take the test, he or she violates Oregon's implied consent law. A prosecutor may use this violation as evidence of criminal behavior in court.