People like having a good time, and that includes having a drink or two. Hopefully, you call a cab to take you home, or you have a designated driver who doesn't drink and can drive you safely to your destination. However, even if you don't drink, you may still be stopped by the police in a random field sobriety test or sobriety stop.

Stopping Your Vehicle

A police officer may stop your car based on a traffic violation or the suspicious motion of your car (this might include weaving, wide turns or riding the center line of the road). You may be stopped at a sobriety checkpoint or roadblock. They're used by the police to keep drunk drivers off the road or to apprehend suspects for some other crime.

While you're still in the car, the officer looks for signs of intoxication based on your responses, both vocal and physical, while asking for your license and registration. The officer may even ask if you've been drinking.

Field Sobriety Tests

Field sobriety tests (FSTs) are used by police officers to identify and arrest drivers suspected of driving under the influence (DUI) or driving while intoxicated (DWI). A breath or blood test may follow in order to determine your blood alcohol content (BAC).

Results from any of these tests are likely to be used as part of the case against you if you're charged with a DUI-DWI offense.

After being stopped by a police officer, you may be asked to perform an FST whether you had a drink or not. Familiarity with the common tests conducted by the police, how the test results are interpreted and used, and the shortcomings of FST methods are things you should know as an educated and prepared driver.

While there is a large body of research supporting the validity and accuracy of FSTs commonly used by police, there is also a lot of controversy about these tests.

Standard Field Sobriety Tests

There are 3 common FSTs from the National Highway Traffic Safety Administration (NHTSA):

  1. One-leg stand test - You're asked to stand with arms down and one foot suspended about six inches above the ground
  2. Walk-and-turn (WAT) test - You're asked to walk a straight line, placing the heel of the stepping foot at the toe of the back foot, turning, and walking back
  3. Horizontal gaze nystagmus (HGN) test - You're asked to track a moving object with your eyes while holding your head steady

In an HGN test, the police officer will move an object, typically a penlight, across your field of vision. The officer watches for a characteristic jerking or bouncing movement (called nystagmus) of your eyes when they're positioned at a far horizontal point. Nystagmus is often present when a person has a blood alcohol content of .10 percent or more.

NHTSA studies have shown that a combination of tests, particularly the WAT and HGN tests, can be very accurate in detecting intoxication at levels of .10 percent or higher. However, it's important to remember that FSTs are designed to detect and measure impairment. They don't reveal the cause of impairment.

Challenging FST Evidence

Your defense attorney may seek to challenge the admissibility of FST evidence at trial in several ways, including the:

  • Police officer's reason for stopping your vehicle
  • Officer's method of conducting and interpreting the FSTs
  • Accuracy of the test results based on your situation
  • Specific use of FST evidence against you in proving your level of intoxication

The accuracy of FST methods may be negatively affected by:

  • Your age, weight and physical condition
  • A wide variety of illnesses and medications, or wearing contact lenses
  • Less-than-optimal roadside testing conditions
  • The police officer's training and skill in conducting and interpreting FSTs
  • Lack of baseline performance against which to judge a driver's FST results

FSTs aren't an exact science, and mistakes are made. If you're involved in a DUI-DWI situation, you should talk to an attorney as soon as possible to make sure your rights are protected.

Questions for Your Attorney

  • What is the blood alcohol level (BAL) for my state?
  • What could happen if I refuse to take an FST or a blood or breath test because I didn't have anything to drink?
  • Could I get cited for DWI/DUI even if I had one drink?

Tagged as: Criminal Law, DUI/DWI, sobriety test, cop test, dui lawyer, dwi lawyer