Police use many different tests during the motor vehicle stop to help them determine whether they believe a suspect is under the influence of liquor or drugs. While some of these tests fall under the category of “Standardized Field Sobriety Tests,” some of the tests are non-standardized and have not been studied to determine the how reliably they can predict intoxication.
Standardized Field Sobriety Testing
In the mid-1970s, the National Highway Transportation Safety Administration (NHTSA) began sponsoring scientific research studies to determine which of the roadside field sobriety tests already used by police officers in the investigation of DWI were the most accurate. It was determined that three of these tests, when administered in a standardized manner, were an accurate and reliable battery of tests for determining blood alcohol content over .10%. (It should be noted that the current legal limit is .08%.) Those three tests were:
When combined, the accuracy of the HGN and WAT together was determined to be 80%. Field validation studies were conducted in the late 1990s in Colorado, Florida, and San Diego.
1).Horizontal Gaze Nystagmus
Nystagmus is the involuntary jerking of the eyes. Alcohol and some drugs cause Horizontal Gaze Nystagmus. When administering this SFST, an officer first checks for equal pupil size, resting nystagmus, and equal tracking (which means that the eyes can follow and object together). The officer will then ask the suspect to follow a stimulus (generally a pen or a finger) using only his or her eyes while the officer moves the stimulus back and forth. The clues the officer is looking for are threefold: (1) lack of smooth pursuit, meaning a jerking or bouncing of the eyes as they follow a smoothly moving stimulus; (2) distinct and sustained nystagmus at maximum deviation, meaning that a nystagmus is present when the eye is held at maximum deviation for a minimum of four seconds; and (3) onset of nystagmus prior to 45 degrees, meaning that the eyes begin jerking prior to 45 degrees.
It must be noted that while the HGN test is utilized by nearly all police agencies and that the New Jersey State Police even give out certifications to officers trained in this procedure, its reliability has never been the subject of a scientific reliability hearing in any New Jersey court and thus, the test itself is not admissible as an indicia of guilt.
2).Walk-and-Turn
During the WAT test, an officer will ask the suspect to stand in a specified starting position while giving the test instructions. The officer will then instruct the suspect to take 9 heel-to-toe steps forward in a straight line, while holding her arms at her sides, looking at her feet, and counting her steps out loud. She is then instructed to execute a turn and walk 9 heel-to-toe steps back in the opposite direction, again holding her arms at her sides, looking at her feet and counting her steps out loud, to complete the test. Some of the clues of impairment that the officer will be looking for are as follows:
According to the research, when a suspect exhibits two or more clues or fails to complete the test, the suspects BAC will be over .10% approximately 68% of the time.
This test is supposed to be given on a flat, dry surface that is clear of any debris, in any area where there is sufficient room to complete the test. Additionally, suspects who are over 65 years of age or who had back, leg or inner ear problems had difficulty completing the test.
3).One-Leg Stand
This test, like the WAT, tests a suspect’s balance. During the OLS, the suspect will be told by the officer to stand with her feet together and arms at her sides. She will then be told to lift the leg of her choosing approximately 6 inches off the ground and hold it there while counting out loud by thousands (one-thousand-one, one-thousand-two, etc.), keeping her arms at her sides while looking at her raised foot. She will be told to continue counting until told to stop (while the officer measures the passage of 30 seconds). She should also be told that if she puts her foot down at any point, she should pick it back up and begin counting again where she left off.
The clues of impairment that an officer is looking for during this test are:
According to the research, a person with a BAC of .10% can maintain their balance for up to 25 seconds, but rarely for the entire 30 seconds, which is why the officer is timing the passage of 30 seconds. Officers are trained that the presence of two or more of these clues, or failure to complete the test, indicates a BAC of .10% or higher about 65% of the time.
This test requires the same testing conditions as the WAT.
Other Field Sobriety Tests
As noted above, there are several other field sobriety tests which are used by police officers in New Jersey. Some of these are: