Can fingernail biting during a DUI breath test observation period require suppression of the Intoxilyzer result? American Fork City v. Barbour Explained

Background and facts

In May 2023, Brandon Barbour was pulled over in American Fork, Utah. Officers detected the odor of alcohol, administered field sobriety tests, and transported Barbour to a neighboring police station for an Intoxilyzer breath test. Before administering the test, Deputy observed Barbour for the required fifteen-minute Baker pretest observation period. Bodycam footage, produced in discovery, showed Barbour biting his fingernails continuously for more than two minutes during that period—stopping less than one minute before the test. The Intoxilyzer registered a BAC of .11. Despite having reviewed the footage and stating at a pretrial hearing that he anticipated filing a motion to suppress, trial counsel never filed the motion. Barbour was convicted of DUI.

Key legal issues

The case presented two questions under the Strickland ineffective assistance framework: (1) whether counsel performed deficiently by failing to move to suppress the breath test, and (2) whether that failure prejudiced Barbour’s defense. Underlying both questions was a subsidiary issue of first impression in Utah: whether fingernail biting during the Baker observation period constitutes introduction of a substance into the mouth sufficient to require the officer to restart the fifteen-minute clock.

Court’s analysis and holding

The Utah Court of Appeals held that fingernails are unambiguously something—not nothing—placed into the mouth, and that Utah’s Baker rule, as articulated in State v. Vialpando, requires the government to show the defendant introduced nothing into his or her mouth during the observation period. Because Deputy never restarted the clock after the prolonged nail-biting, the foundational requirements for admitting the Intoxilyzer result were not met. Counsel’s failure to file a suppression motion was therefore objectively deficient performance; the worst-case scenario if the motion had failed was the conviction that occurred anyway, making suppression a battle competent counsel would have fought.

On prejudice, the court applied its prior analysis from State v. Harvey to conclude that the remaining evidence—one brief median crossing, some FST clues, an odor of alcohol, and Barbour’s admission to consuming two shots and two beers—was insufficient to support conviction under the impairment prong of Utah Code § 41-6a-502(1)(b). Without testimony about specific FST failures, slurred speech, droopy eyelids, or erratic driving, there was a reasonable probability that a jury would not have convicted absent the breath test. The court vacated the DUI conviction and remanded for a new trial.

Practice implications

This decision carries significant consequences for both DUI defense and prosecution. Defense counsel must scrutinize all bodycam footage of the Baker observation period before deciding whether to file a suppression motion—overlooking that review may itself give rise to an ineffective assistance claim on appeal. Prosecutors should ensure officers document in their reports and testify specifically about any observed behaviors during the observation period and, where the clock has not been restarted, be prepared to defend the foundational admissibility of the Intoxilyzer result. The opinion also reinforces that FST evidence alone, without corroborating behavioral indicators of incapacity, is unlikely to sustain a DUI conviction under the impairment prong when BAC evidence has been excluded.