What are the field sobriety tests? Do I have to do them?

The field sobriety test is generally made up of 3 parts, the horizontal gaze nystagmus, the walk and turn, and the one leg stand. There is also a forth part of the field sobriety testing called the portable/preliminary breathalyzer test.

The tests are voluntary meaning that you do not have to do them. If you elect to do them, there is a good chance you will fail. However, your refusal to do them will be considered evidence that you refused them because you were guilty. You are damned if you do, damned if you don't. Often, the police have already decided to arrest you before even before asking you to take the test and they are just wanting to gather more evidence that will later be used to try and convict you.

The tests are somewhat controversial in that the National Highway Traffic Safety Administration (NHTSA) has touted these tests as being scientific and highly accurate in predicting levels of intoxication. This understanding has trickled down to law enforcement agencies and to the courts. The tests are now generally accepted by these groups as being generally accurate, reliable, and admissible. The basis for the scientific accuracy of these tests is mainly due to three validation studies contracted by NHTSA. The studies are well worth looking at, but are not the topic of this blog post.

The first test is the horizontal gaze nystagmus, or HGN. Nystagmus is can be described as a twitching or bouncing of the eye as is moves back and forth. The description often given by law enforcement is a windshield wiper on a dry windshield.

There are three portions of the tests, checking for smooth pursuit, distinct and sustained nystagmus at maximum deviation, and onset of nystagmus prior to 45 degrees. The maximum score one can reach is a 6/6, meaning that all of these clues would be present in each eye. Even a 4/6 is a "failing" score. 

This is the one that is most heavily relied on. However, there are many causes of nystagmus and many have nothing to do with intoxication. In fact, everyone has naturally occurring nystagmus to some degree.

The next test is the walk and turn. You are asked to take nine heel-to-toe steps down an invisible line, shuffle around to face back down the line, and take nine heel-to-toe steps back to the starting point. There are eight "clues" that can be observed. A score of two is a failing score. The clues are stepping off of the invisible line, not stepping heel-to-toe, doing an incorrect number of steps, doing an improper turn, raising your arms more than six inches, being unable to maintain balance, and starting the test too soon.

The final test in the battery of tests is the one leg stand. You are to count out loud for thirty seconds while raising one leg about 6 inches off of the ground. There are four "clues" for this test. A score of 2 is a failing score. The clues are swaying, hopping, putting your foot down, and using your arms to balance.

The field sobriety test manuals used to say that the tests had to be done in a standardized manner, i.e., the same way every time. The language stating this has been watered down or altogether removed over time. 

Again, the tests are not solely tests of agility. If you get bored while the officer is giving you the instructions for the walk and turn test and move your feet out of the starting position, you already have one point. One more, and you have failed the test.

After the field sobriety tests are done, you will usually be asked to take a roadside breathalyzer. The results of the roadside breathalyzer are not admissible in court. The officer is supposed to tell you that. If you blow over the limit, you are almost guaranteed to be arrested. If you blow under, you may still be arrested. If you refuse the portable breath test, your refusal may be used against you later and you will probably still be arrested.

Since this roadside breath test is not admissible and will give you a general idea of what your BAC will be at the police station, you may want to do it and find out so that when you are provided the opportunity to call an attorney at the station, you can let them know what your BAC was and when your last drinks occurred. This can help the attorney to advise you as to whether or not to take the actual BAC test that can be used against you in court.