Challenging the HGN field sobriety tests in DUI defense

By: Steven Rauchman, MD

In this compelling episode of The Science of Toxicology Testing, I join host Aaron Olson to critically examine the validity of the Horizontal Gaze Nystagmus (HGN) test, a standard component of roadside sobriety assessments in DUI cases. As a board-certified ophthalmologist with over 30 years of clinical experience and a respected medical-legal expert witness, I explain why this test lacks scientific rigor and can result in false positives, even in sober individuals.

Drawing on my background in trauma ophthalmology, visual science, and med-legal work involving traumatic brain injury (TBI), I shed light on the medical complexities that officers are unequipped to evaluate. I also highlight the systemic flaws in relying on subjective observations by non-medical personnel to establish probable cause, raising serious constitutional and evidentiary concerns for defense attorneys.

Key topics discussed

Medical and legal flaws in HGN testing, explained

• The flawed science behind the HGN test

  Why the test lacks a reliable scientific foundation and how that undermines its courtroom credibility.

• Why officers lack the medical training to assess nystagmus accurately

  Nystagmus detection requires advanced medical expertise—not 30 hours of police instruction,

• False positives in sober individuals and their legal implications

  How HGN can wrongly suggest impairment, leading to potential wrongful arrests and prosecutions.

• The constitutional tension between HGN use and probable cause

  An analysis of how HGN testing may violate Fourth Amendment protections.

• Proposals for courtroom admissibility and more objective alternatives

  Options for defense attorneys to challenge HGN evidence and advocate for medically sound alternatives.

• My efforts to publish peer-reviewed critiques and testify in court as a DUI defense expert witness

  How I'm working to bring expert medical analysis into the courtroom to support just outcomes.

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Listen to the full episode

“The Eyes Have It (Wrong): Horizontal Gaze Nystagmus Through an Ophthalmologist's Skeptical Lens”
Host: Aaron Olson | Duration: 28 min

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Why this matters for DUI defense attorneys

If you're representing clients in DUI cases, particularly those involving field sobriety tests, this podcast offers expert medical insight that could strengthen your defense strategy. My expertise is particularly relevant in Frye and Daubert hearings where the admissibility of HGN findings is contested. I provide both written opinions and courtroom testimony, and I’m available for consultation nationwide.

Let’s work together to ensure that science, not speculation, informs justice.

Contact me directly

• Email: Dr.Rauchman@yahoo.com

• Call: (818) 620-0115