Boulder is not alone in sometimes using eyelid tremor as one of the “roadside maneuvers.”  These voluntary tests are intended to identify impaired drivers. Part of the standard police roadside gymnastics to identify recent THC/marijuana use is to claim to observe “eyelid tremor.” In a study first posted on-line in February, 2024, that belief is called into serious doubt. The study, largely Colorado based including significant involvement from the University of Colorado and Anschutz Medical Center

The strong local research participation ties are spelled out in the opening to the study, with all of the science talent and contribution coming from Colorado. Again we are at the forefront of research!

University of Colorado Anschutz Medical Campus, Children’s Hospital Colorado, Aurora, CO, USA; University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Departments of Ophthalmology, Neurology, and Neurosurgery, Sue Anschutz-Rodgers University of Colorado Eye Center, Aurora, CO, USA; Department of Biostatistics and Bioinformatics, Emory University, Atlanta, GA, USA; Department of Biostatistics, Medpace, Denver, CO, USA; fDriving Safety Research Institute, College of Engineering, University of Iowa, Iowa City, Iowa, USA; Institute of Cognitive Science, University of Colorado Boulder, Boulder, CO, USA; Injury and Violence Prevention Center, University of Colorado Anschutz Medical Campus, Aurora, CO, USA

[NO LEGAL ADVICE is intended or offered. All cases are different, and this blog is general. Accuracy is a goal, and is absolutely NOT to be relied upon. ]

Eye tremor has long been used to help build cases against people charged with driving under the influence of marijuana, DUID, DWAI, or Driving Under The Influence of Drugs. More serious charges can also result. Eyelid tremor has been presented by prosecutors, state “experts,” and used by LEOs Law Enforcement Officers to show “recent consumption of THC.” This latest study finds that eyelid tremor cannot even be consistently identified by experts in the lab. It almost certainly cannot be consistently judged by officers in the field with the collection of flashing lights, poor lighting, and the rest of what makes the roadside different than a lab.

Even if the tremors can be properly identified, which they apparently cannot be, there is no scientific connection between eyelid tremor and recent THC use. Erroneously, the Drug Evaluation and Classification Program of the International Association of Chiefs of Police has eyelid tremor included in their practice and within their roadside testing to “show” recent consumption. BUT it turns out that the tremor may just as well be from worms on DUNE if the tremor can be identified at all.

While the statistics language which describes the results is a tad daunting, meaning I did not understand the formal statistics, I DID understand this statement from the study.

“The weak association between recent cannabis use and eyelid tremor does not support its utility in identifying recent cannabis use.”

That is quite clear. Eyelid tremor is not useful in determining recent THC use. Your marijuana-knowledgeable lawyer should be aware of this most recent study if part of the simple roadside maneuvers included claims of eyelid tremor. Remember that the roadside maneuvers like “walk the line” and “touch your nose” are legally, in Colorado, VOLUNTARY! They do not have to be preformed if that is the driver’s choice. My experience in Court is that the roadside circus almost never helps the alleged driver. Far more often, regardless of how someone thinks they did on the testing, the results are used at trial to help get a conviction. That would be fine IF the tests were useful in showing impairment, were performed properly, and the results were properly observed. Eyelid tremor fails in all three categories and should not be a part of the roadside maneuvers.  Do not get confused. If a LEO asks you to choose a blood test or a breath test, or asks you to take a blood test, refusal is used as evidence of guilt, and your license will almost certainly be gone for a year. No red license, do not pass go, do not collect $200.00 The stakes for refusal are high. That does not apply to voluntary roadsides. Here’s language from the conclusion.

“In a cohort of participants with a range of cannabis use histories, acute cannabis smok-
ing was not associated with the presence of eyelid tremor, regardless of cannabis use history, at 70
minutes post-smoking.”

While people who drive while impaired are dangerous to themselves as well as to the rest of us, people that are NOT impaired and even those who ARE impaired should not be convicted based upon what is shown to be scientific nonsense. Let’s rely upon evidence which has merit in proving a case. A courtroom has time for relevant science. We do NOT have time for science fiction! Facts! Not fantasy!

stay legal and safe

Lenny Lensworth Frieling

Shared Knowledge is Power!


  • Senior Counsel Emeritus to the Boulder Law firm Dolan + Zimmerman LLP : (720)-610-0951
  • Former Judge
  • Photographer of the Year, AboutBoulder 2023
  • First Chair and Originator of the Colorado Bar Association’s Cannabis Law Committee, a National first.
  • Previous Chair, Boulder Criminal Defense Bar (8 years)
  • Twice chair Executive Counsel, Colorado Bar Association Criminal Law Section
  • NORML Distinguished Counsel Circle
  • Life Member, NORML Legal Committee
  • Life Member, Colorado Criminal Defense Bar
  • Board Member Emeritus, Colorado NORML
  • Chair, Colorado NORML, 7 years including during the successful effort to legalize recreational pot in Colorado
  • Media work, including episodes of Fox’s Power of Attorney, well in excess of many hundreds media interviews, appearances, articles, and podcasts, including co-hosting Time For Hemp for two years.
  • Board member, Author, and Editor for Criminal Law Articles for the Colorado Lawyer, primary publication of the Colorado Bar Assoc. 7 Years, in addition to having 2 Colorado Lawyer cover photos, and numerous articles for the Colorado Lawyer monthly publication.
  • LEAP Speaker, multi-published author, University lectures Univ. of Colorado, Boulder, Denver University Law School, Univ. of New Mexico, Las Vegas NM, and many other schools at all levels.