Testing for Drunk Driving

Drunk driving, or driving under the influence, means that a person’s ability to drive has been impaired by the consumption of alcohol. In the United States, the amount of alcohol in a person’s system can be determined quickly through a breathalyzer test. Other ways to test a person’s blood alcohol level include blood tests, urine tests, and sobriety field tests.

In some states, a driver can choose which test he or she wants to take, but if the test reveals a level of intoxication of 0.08% or higher, the person is legally considered to be driving drunk. A driver must submit to all of these tests, with the exception of the field tests, if a police officer requests one. In some states, failure to do so results in a driver losing his or her license for up to one year.

Sobriety field tests are commonly performed on the side of roads or in a safe place off of a roadway to help police officers determine if a driver is under the influence of alcohol or drugs. If a driver performs poorly in any of the various tasks associated with field tests, the officer has probable cause to arrest the person for alcohol impaired driving, and the test results may be used as proof in a court of law. An officer also has the right to arrest a driver solely based on the observation of the driver’s behavior, although normally a blood, breath, or urine test is also required.

There are many different types of field tests that an officer can request. Oftentimes, a person is asked to walk in a straight line, stand on one leg, or recite the alphabet or a group of numbers. In other field tests, an officer positions an object, usually a pen, about one foot from the driver’s face and then moves the object from one side to another while observing the driver’s eye movements. If there is any involuntary jerking or trembling in the eyes, the driver has most likely been drinking.

Another test requires the driver to take nine steps, heel-to-toe, along a line and then turn and come back to repeat the process. In this test, the officer assesses whether or not the driver is able to keep his or her balance and follow instructions. Usually, if a driver has been drinking, he or she leaves space between heel and toe, has trouble taking steps in a straight line, or stops during the test.

Simple field tests, which evaluate a person’s coordination and balance, include having a person stand with heels together, arms at the side, and raise one leg about six inches from the ground while counting aloud. Also, a person may be asked to stand feet together, eyes closed, and arms extended while touching the index finger to the nose.