The “science” in field sobriety tests is laughable.
Here is my article that has been published nationally:
Judge Daryl Coffey of County Criminal Court number 8, in Tarrant County, Texas once remarked to me that all a prosecutor has to do to win a DWI case is just make sure that the three letters “DWI” are mentioned at least 15 times in a trial.1 It is this type of environment that has allowed history to repeat itself. All we have to do is look back to the Salem Witch Hunt trials of 1692 where 19 convicted “witches” lost their lives on “specter” evidence. Evidence in DWI trials has not come a long way from 1692 where claims of apparitions only visible to their victims were enough to get one hung. The greatest challenge to DWI practitioners these days and to those accused of DWI/DUI related crimes is that courtrooms have not kept pace with the science. Bad science is rubber stamped with approval by the majority of the judiciary as long as the government sponsors it. Horizontal Gaze Nystagmus
The horizontal gaze nystagmus test, or HGN, is alleged to be 77% accurate (80% accurate with the W&T) in determining if a person is .10 BAC3 or more.4 The first problem with this test is the particularity. Police officers are not ophthalmologists trained in the detection of eye movements and or eye pathologies. There are forty-seven types of nystagmus in individuals, separate from Horizontal Nystagmus: