Police Officer Was Not Qualified to Testify as an HGN Expert

Written on Monday, October 26th, 2020 by T.C. Kelly
Filed under: Expert Opinions, ExpertWitness, Working with Experts

Kayin Love was charged with driving under the influence of alcohol (DUI). She appealed her conviction, contending that the arresting officer should not have been permitted to testify as an expert witness.

In an unpublished opinion, the Maryland Court of Special Appeals concluded that a police officer must be qualified as an expert to give testimony about the horizontal gaze nystagmus (HGN) test. The court ducked the issue of whether the arresting officer was an expert by concluding that the trial court did not regard the officer as an expert. The court then faulted the defense attorney — who had already objected that the officer was not qualified to testify about the HGN — for not objecting again when the officer testified about the HGN result.

Facts of the Case

Officer Robert Farmer testified that Love did not stop her vehicle behind the crosswalk of an intersection. Although she stopped before she entered the intersection, the vehicle encroached upon the crosswalk in violation of Maryland law.

Farmer detained Love and questioned her while she still in the driver’s seat. Farmer gave familiar testimony that Love had a flushed face and watery, bloodshot eyes. He asked Love if she had been drinking and she said she had one drink and one beer an hour and a half before she started driving. That quantity of alcohol in that time frame would not cause most drivers to exceed the legal limit.

A second officer arrived who apparently had more familiarity with the process of making DUI arrests. Officer William Weill provided inevitable testimony that he smelled the odor of alcohol coming from Love’s vehicle — an odor that Farmer apparently failed to detect.

Weill administered a walk-and-turn test, a one-leg stand test, and a horizontal gaze nystagmus (HGN) test to Love. Based on Love’s performance on those field sobriety tests, Weill decided he had probable cause to arrest Love for DUI.

Field Sobriety Tests

The three standardized field sobriety tests that Weill administered were developed and endorsed by the National Highway Traffic Safety Administration (NHTSA). The same contractor that developed the tests for NHTSA also validated the tests. The validation assessed the tests in controlled laboratory conditions, not as they are actually administered — on the side of road, often on an uneven surface, at night, in a variety of weather conditions. The agency’s failure to subject the tests to real-world validation and to an objective peer-review process suggest that NHTSA was more interested in helping the police justify arrests than in producing good science.

While courts routinely regard the standardized field sobriety tests as evidence that a driver has a blood alcohol content in excess of the legal limit, the tests were developed with little scientific rigor. An independent analysis of the tests found that “research that supports their use is limited, important confounding variables have not been thoroughly studied, reliability is mediocre, and that their developers and prosecution-oriented publications have oversold the tests.”

Even NHTSA agrees that the tests are not valid unless the arresting officer follows the exact procedure described in the training manual. On cross-examination, officers often reveal that they can’t recall the details of the procedure they are supposed to follow.

A larger issue arises when officers testify that the tests are valid. Officers claim the tests are valid because NHTSA says they are valid, not because the officers are familiar with the research methodologies that underlie the tests. Traffic officers simply lack the scientific knowledge and education that is required to give an expert opinion about the validity of field sobriety tests.

The HGN Test

The most doubtful of the three standardized tests is the HGN. The test assumes that a driver has a blood alcohol concentration in excess of 0.08 based on whether and when the driver’s eyes “twitch” or “jerk” while following a pen or some other object.

All eyes twitch (that is, they all show nystagmus) when people move their eyes as far as they can to the left or right. According to NHTSA, there is a correlation between an unlawful blood alcohol concentration and the onset of twitching before the eyes reach a 45-degree angle as they move to the left or right.

Unfortunately, eyes might twitch for dozens of other reasons, particularly if the driver is facing oncoming headlights or gazing in the direction of the police car’s flashing red-and-blue lights. Perhaps more problematic is that the validity of the test result depends on the officer’s accurate determination of whether the driver’s eyes have reached a 45-degree angle. Since officers do not carry a protractor in their tool belts, their estimates are unverifiable and may be wholly unreliable.

Even when the officer performs the HGN perfectly, NHTSA found that the test produces an inaccurate result 22{d61575bddc780c1d4ab39ab904bf25755f3b8d1434703a303cf443ba00f43fa4} of the time. Other researchers have determined that nystagmus may appear before the eyes reach a 45-degree angle in drivers who are well under the legal limit. Given the frequent reliance on HGN results as trial evidence, whether a test that is so prone to error meets the reliability standard of Daubert is an important question.

Weill’s Expert Testimony

At Love’s trial, Weill testified that he had “specialized training in alcohol-related offenses,” consisting of the 40-hour course that most police officers take before they are assigned to traffic duty. He also testified that he had made a large number of DUI arrests, although that testimony sheds little light on whether he conducted field sobriety tests correctly before he made the arrests.

Courts commonly hold that police officers can testify about HGN results if they have been “trained.” Yet the training only teaches officers how to administer the test. Whether the test itself satisfies the Daubert requirement that expert evidence must be based on sufficient facts and a sound methodology is not the subject of law enforcement training. Learning how to administer a test is not the same as learning whether the test has a sound scientific basis.

When Weill testified that he performed an HGN test on Love, defense counsel objected that Weill was not qualified to testify as an expert witness regarding the validity or interpretation of HGN test results. The prosecutor initially indicated that Weill would not be asked to testify about the HGN results but proffered Weill as an expert on the other two field sobriety tests. After a confusing colloquy, the court agreed that Weill was an expert on the strength of his testimony that he had been “trained.” Weill then testified about the HGN test result.

The appellate court acknowledged that Maryland precedent requires an expert witness to testify about HGN results. Weill was clearly not an expert. The appellate court overcame that obstacle by deciding that the trial court did not actually intend to qualify Weill “as an expert regarding the HGN test.”

The appellate court concluded that Love’s objection — “the State had failed to lay a sufficient foundation to qualify Officer Weill as expert with respect to the standard field sobriety tests” — did not address Weill’s testimony about the HGN test because the prosecutor claimed that Weill would not testify as an expert regarding that test. According to the appellate court, when the trial court ruled that Weill could testify as an expert, the ruling only applied to Weill’s testimony regarding the other two field sobriety tests. Because defense counsel did not object to Weill’s lay testimony about the HGN results — testimony that was plainly improper under Maryland law — she failed to preserve the issue for appeal.

Lessons Learned

Courts often bend over backwards to preserve DUI convictions. This appears to be one of those cases. The prosecutor clearly understood that the trial judge had agreed that Weill could testify as an expert regarding the HGN. Since the admissibility of an HGN result depends on a foundation of expert testimony, it would have been improper for the prosecutor to try to place the test results before the jury through lay testimony. It seems disingenuous to conclude that the trial judge and parties did not believe that Weill was testifying as an expert. Since there was no evidence of his expertise, the testimony should not have been allowed.

It is always problematic when police officers testify as expert witnesses. It is even more problematic when an officer testifies as an expert to support the officer’s own decision to make an arrest. The testimony is inevitably self-serving and rarely helpful to the jury. While defense attorneys should always object to police officers who testify as expert witnesses, Love’s case is a reminder that those objections should be lodged against every question that asks an officer to give testimony that only an expert witness is qualified to provide.


About T.C. Kelly

Prior to his retirement, T.C. Kelly handled litigation and appeals in state and federal courts across the Midwest. He focused his practice on criminal defense, personal injury, and employment law. He now writes about legal issues for a variety of publications.

About T.C. Kelly

Prior to his retirement, T.C. Kelly handled litigation and appeals in state and federal courts across the Midwest. He focused his practice on criminal defense, personal injury, and employment law. He now writes about legal issues for a variety of publications.