I taught a continuing education seminar yesterday at UC Law School. My focus was on the validity of the Horizontal Gaze Nystagmus test, or HGN. This is a bouncing of the eye as it gazes to the side.
This the first test done on most DUI suspects in the Dayton Ohio area. The officer will ask you out of the car and tell you they are going to check your eyes.
They ask if you have contacts or glasses. They do a medical check by asking about eye problems, trauma, and recent illness.
If you pass they then check your eyes. The National Highway Traffic Safety Administration or NHTSA publishes a manual on field sobriety testing that shows an officer how to do the test.
The manual also claims that the test is accurate if done properly. This test requires the officer to move a pen or finger at a certain pace a certain distance from the subject’s face at a certain distance above eye level.
The also have to face the suspect away from flashing lights and traffic. In response to lawyers attacking improper administration of the test NHTSA commissioned another test.
They titled it the Robustness of the HGN test. As you can guess they concluded that no matter where you put the stimulus or how you move it, HGN is still present.
What they ignore is that the test was wrong more than it was right at predicting people with BAC levels over the legal limit. In fact they found HGN in subjects with a little as one beer in their system about 1/4 the legal limit and according to the test results that means they should have tested over the limit. One battery showed correct results only about 25% of the time or half as good as flipping a coin!
The only thing the Robustness report says to me is that HGN Happens and they have no idea why. And of course it does not matter how they do the test because HGN is present in OVI suspencts in Dayton Ohio that only drink one beer.