Challenging Scientific Evidence and Testimony in DUI Cases
The standards for challenging “scientific evidence” in drunk driving litigation.
“Scientific evidence” in DUI cases is not always considered scientific, reliable or admissible in court. To best illustrate this point, let’s look at the plight of the Horizontal Gaze Nystagmus (HGN) test, which is the eye test commonly given in DUI cases.
Up until the past decade, the HGN test was considered unreliable by most courts, and most courts would therefore not let such pseudo-science into court. Arizona DUI law was on the forefront of allowing its use in evidence, and today more and more states are starting to fall in line.
HGN is good for diagnosing “neuralgic dysfunction, one cause of which may be alcohol.” This used to be all that law enforcement officers could testify to. Through slowly chipping away at the courts, prosecutors have been able to sell the notion that HGN is scientific when applied by an officer in the field. It doesn’t matter that many officers can’t even pronounce the word “nystagmus” let alone describe the complex neurological process by which it is created and manifested.
No matter. NHTSA studied it and found that it was present in a high percentage of heavily dosed drunk drivers, and their published findings are now paving the way for this test to be used against DUI defendants around the world.
There are two basic standards for admitting “scientific” evidence into DU trials, and the method depends on the state:
The Frye Standard: Under this standard, if the method to be testified to is “generally accepted in the scientific community” then it comes into evidence. The question becomes, what is the “scientific community.” For this reason, law enforcement forensic scientists have taken to forming their own scientific communities.
The Daubert Standard: Under this standard the evidence must be:
- Relevant (in other words, it must fit the facts of the case); and
- It must be reliable and derived from the scientific method (meaning that it was empiricly tested, peer reviewed or published, subject to know and quantifiable standards, and/or generally accepted in the scientific community).
Regardless of which standard is used in the state where your DUI is pending, a DUI defense lawyer can challenge the admission into evidence of scientific evidence by requesting a Frye or a Daubert hearing. If the issue has already been litigated and settled, your attorney may advise against re-litigating it due to the high expense of doing so (expert witnesses cost a lot of money), and the slim chance of changing the law. If, on the other hand, the evidence proffered by the state is novel or doesn’t fit into a past-accepted format, it is imperative that your DUI lawyer challenge the evidence.