Interviewer: What is the purpose of the field sobriety tests?
Ron Mondello: Most people, if you were to ask them that question, would obviously say that it’s to figure out whether or not someone is drunk. That’s typically it. There is, of course, some history associated with the field sobriety tests, and there’s a differentiation between standardized testing and non-standardized testing. I think we’re probably going to be speaking, at least first and foremost, about the standardized testing.
Police Officers Utilize Field Sobriety Tests to Determine Whether or Not Somebody’s Driving is Impaired Due to Alcohol
For many years we all know that police officers have utilized field sobriety tests to determine whether or not somebody driving is impaired due to alcohol. The performance of the person on those field sobriety tests is used by the police officer to develop what’s known as probable cause for the arrest, and then of course they use it as evidence in court.
Especially in New Jersey, as in most states, the prosecution or the state will come at you in a two-pronged approach. The first prong is you take the Breathalyzer. If you blow something over a 0.08 or above, you are, per se, intoxicated, but if for some reason the blood alcohol level or the reading doesn’t come into evidence, like if there’s some type of defect or some problem with the machine, then the state can still rely on observations.
These standardized tests, along with other observations, are used in court by the state as evidence to try to convict you of driving while intoxicated. There were a wide variety of field sobriety tests back then and there was a need to develop a standardized set of tests.
History of Field Sobriety Tests
If I could just briefly go into a little bit more history, it started back in 1975, and there were quite a few scientific research studies that were going on with the National Highway Traffic Safety Administration, and they were working in concert with the Southern California Research Institute to try to figure out which one of these field sobriety tests or what combination of these field sobriety tests would be the most accurate. These organizations traveled to various law enforcement agencies throughout the United States and tried to answer that question.
After a lot of laboratory research and “in the field” research, they determined that there were three tests that were highly accurate and very reliable for distinguishing blood alcohol readings above 0.10. Of course, that’s when the level of intoxication was 0.10. Now of course they’ve redone some research on this. The same tests are considered to be highly accurate and reliable for determining whether somebody’s BAC (blood alcohol concentration) is above a 0.08.
Those three tests are the Horizontal Gaze Nystagmus (or “HGN” for short), the walk-and-turn, and the one-leg stand. They were able to put together standardized practical and effective procedures so that every police officer used the same procedure so that you didn’t get erratic results. Those three standardized tests were found to be highly reliable and they’re very much used today.