There are a number of testing methods used to determine whether a driver was intoxicated at the time of arrest. Each procedure must follow certain requirements in order to be valid. DUI cases often turn upon the quality of the testing evidence.

Field sobriety tests

Field sobriety tests involve performing physical activities. Failing to adequately perform the activities can indicate a lack of sobriety. There are three standard field sobriety tests, although others may be used as well. One test is referred to as the “Walk and Turn” test. In this test, the driver must stand with his feet lined up heel–to–toe while instructions are given, and then must walk nine steps heel–to–toe, turn, and walk back nine steps, counting aloud during the test. Another field sobriety test is called the “One–Legged Stand” test. The driver must raise one leg six inches or so off the ground, and count aloud while looking at the elevated foot. The third common field sobriety test is the Horizontal Gaze Nystagmus test. In this test, the officer has the driver follow a small object with his eyes. Nystagmus is an involuntary jerking of the eye when looking to the side, and when an individual is intoxicated, the jerking becomes more noticeable.

In all field sobriety tests, the officer looks for clues of intoxication, including swaying, loss of balance, not following instructions, counting incorrectly, and other commonplace signs of intoxication.

Breath tests

Breath tests are the most commonly–used testing method to determine blood alcohol content (BAC). Typically a portable testing device is used to determine probable cause for arrest, and a second test is administered using a more advanced device at the police station. These are sensitive devices and can be subject to error. Alcohol from other parts of your mouth or from your stomach can enter the device and cause an artificially high reading. The devices must be cleaned and calibrated following established procedures.

Urine tests

Urine tests are considered the least reliable method of testing, and often are used only for testing the presence of drugs. The concentration of alcohol in urine is higher than that of alcohol in blood at the same time, and can lead to inflated test results.

Blood tests

Blood tests for alcohol levels must be administered according to specific procedures and guidelines. The vials that store the blood contain chemicals and must be up–to–date and properly sealed. If not frozen promptly, blood samples can begin to ferment, raising the level of alcohol in the blood.

An experienced DUI defense attorney understands the nuances of each of these testing methods, and can make sure that all required procedures were followed in your case. At A. Scott Grabel & Associates, we will thoroughly pursue all testing issues in your case and advise you of all of your options. Call us today at (800) 342–7896 for a confidential consultation.