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The Purpose of the Field Sobriety Tests

The Purpose of the Field Sobriety Tests

At the conclusion of the Pre-Arrest Stage of a DUI case the arresting officer has to make a decision.  If the officer is reasonably satisfied that his “investigation” has yielded evidence of Drunk Driving, he will proceed to the next phase by asking the driver to exit the vehicle to perform some “routine” tests.  These are referred to as Field Sobriety Tests and, in some cases, the Preliminary Breath Test.

There is nothing “routine” about these tests!

At the time the officer asks the driver to exit the vehicle he’s continually making observations and gathering evidence.  His goal is to gather enough evidence to establish the probable cause required to make an arrest.  For example, the officer observes whether the driver easily opens the door, leaves the vehicle in gear or uses the vehicle for support and balance.

As a practical matter, my training and experience leads me to conclude that the officer has already decided to make an arrest before he asks the driver to exit a vehicle.  Therefore, once the driver has exited the officer’s primary goal is to gather sufficient evidence to convict the driver.

Frequently, this evidence derives from the officer’s observations of the driver’s performance on the Field Sobriety Tests and the results of a Preliminary Breath Test.  These “routine” tests are a critical aspect of a DUI case.

Until the middle of the 1970s, police departments across the country employed a variety of field sobriety tests to enforce Drunk Driving laws.  Due to the lack of consistency, in 1977 the National Highway Traffic Safety Administration commissioned a study to identify the best standardized tests for officers to use.  The 1977 study had three (3) stated objectives:

(1)  To evaluate currently used physical coordination tests to determine their relationship to intoxication and impairment,

(2)  To develop more sensitive tests that would provide more reliable evidence of impairment, and

(3)  To standardize the tests and observations, and thus to give police more consistent evidence for use in Court.

Under intense criticism from the scientific and legal communities, only four (4) years later the National Highway Traffic Safety Administration commissioned another study to develop standardized “scoring” criteria.

The purposes of the 1981 study were to:

(1)  Standardize the administration and scoring procedures,

(2)  Determine the reliability and validity of the standardized tests in the laboratory, and

(3)  Assess the feasibility, utility, and validity of the tests in real life situations.

As a result of the 1981 study, the National Highway Traffic Safety Administration reduced the number of standardized tests from six (6) to three (3).  The tests that survived include the:

(1)  Walk and Turn,

(2)  One Leg Stand and

(3)  Horizontal Gaze Nystagmus.

Officially, the National Highway Traffic Safety Administration recognizes only these three (3) Field Sobriety Tests and discourages reliance upon other field sobriety tests such as the Rhomberg Balance, Finger to Nose, Counting Backward and Letter Cancellation tests.

Today, each Field Sobriety Test is administered and scored with a specific number of scoring points or clues.  If the suspected driver exhibits a designated number of clues in each test, the National Highway Traffic Safety Administration guidelines claim that the driver can be determined to have a blood alcohol concentration above the .10, which is above the legal limit in Rhode Island.