HGN Eye Field Sobriety Test Now Admissible in Pennsylvania DUI Probable Cause Hearings

Many people are familiar with the term sobriety tests in driving under the influence investigations. The Standardized Field Sobriety Tests (SFSTs) are the walk-and-turn, one-legged stand, and horizontal gaze nystagamus (HGN), and these tests have been used by the police in Pennsylvania DUI cases for years. What many non-DUI defense attorneys did not know is that the results of the  HGN, commonly called the eye test, were not admissible in Pennsylvania courts.

As a State College DUI defense lawyer, I often wondered why officers administered the test when they were not permitted to testify about the HGN results. Some Centre County law enforcement officers informed me that HGN test actually gave the officers a very good idea of the driver’s level of intoxication, so the officers conducted the test for their own investigative purposes even if the results were not admissible.

Admissibility of Scientific Tests in Pennsylvania

In Pennsylvania, in order to have the results of scientific tests admitted into evidence, the party presenting the evidence must show that the test is generally accepted by scientists in that scientific community. The purpose behind the law is to only admit results from tests that have gained general acceptance in the particular scientific field. Basically, the courts will not consider evidence that is the product of junk science, meaning that it is only recognized by a few scientists and not the overall scientific community.

At one point, prosecutors tried to use HGN results in Pennsylvania drunk driving cases, but the prosecution never presented sufficient evidence to show that the test was approved by the scientific community. While the test was admissible in courts in many other states, it was not admissible in Pennsylvania. One of the last cases dealing with the admissibility of the HGN was a State College driving under the influence case in which the Centre County judge did permit a jury to hear testimony about the HGN, but, on appeal, the Superior Court held that the Bellefonte judge had erred and reversed the DUI conviction. That case was decided in 1996.

Pennsylvania Permits HGN Testimony in Probable Cause Hearing

In the case of Commonwealth v. Weaver, the Pennsylvania Superior Court issued a precedential opinion that the results of HGN testing are admissible at any hearings related to a court’s consideration of probable cause, but the results are still not admissible at an actual trial. In Pennsylvania DUI cases, criminal defense lawyers sometimes file pretrial motions seeking the suppression of blood alcohol evidence and argue that the arresting officer did not have probable cause to arrest the person. The court’s decision means that an officer will be permitted to testify about HGN results before a judge considering the pretrial motion, but the officer could not present the same testimony to a jury at a trial.

Aside from sobriety tests, officers are also permitted to use portable or preliminary breath tests (PBTs) in DUI investigations. While the officer obtained an alcohol concentration level reading on the breath test device, the actual reading on the device is not admissible at a trial. Instead, officers are only permitted to testify that a PBT was given and the result was either positive or negative for the presence of alcohol.