If you are charged with DUI in Utah, the prosecution will often rely heavily on a chemical test result to try to convict you. Most people assume breath test results automatically come into evidence. They do not.
Before a breath alcohol test can be admitted in a Utah DUI case, the State must establish a proper legal and scientific foundation. If law enforcement fails to follow required procedures, the chemical test may be excluded entirely.
A recent Utah Court of Appeals decision, State v. Montgomery, 2026 UT App 77 (Filed 05/14/2026) significantly strengthened DUI defense challenges involving improper breath testing procedures.
Utah DUI Chemical Testing
Utah DUI investigations commonly involve:
- breath testing,
- blood testing,
- urine testing,
- portable breath tests (PBTs), and
- Field sobriety testing.
Breath testing is governed by:
- Utah Code § 41-6a-515,
- Utah Administrative Code R714-500-1 through R714-500-13,
- and case law.
Primarily State v. Baker, 355 P.2d 806 (Wash. 1960) (en banc);
State v. Relyea, 2012 UT App 55, ¶ 29, 288 P.3d 278; and
State v. Vialpando, 2004 UT App 95, ¶ 14, 89 P.3d 209; State v. Montgomery, 2026 UT App 77
The Utah administrative rules establish standards for:
- certification of intoxilyzer machines,
- operator certification,
- technician qualifications,
- calibration procedures,
- and breath test administration.
But courtroom admissibility ultimately depends on whether the State can establish a proper foundation.
The Foundation Required to Admit a Utah Breath Test
Utah courts have long required the prosecution to establish three foundational requirements before a breath alcohol test may be admitted into evidence.
The Utah Court of Appeals summarized the rule in State v. Montgomery:
To establish the reliability of breath alcohol test results, the State must show that:
(1) the machine had been properly checked by a trained technician, and that the machine was in proper working condition at the time of the test; See admin rule R714-500-1 through R714-500-13.
(2) the test was administered correctly by a qualified operator; and
(3) a police officer observed the defendant during the fifteen minutes immediately preceding the test to ensure that the defendant introduced nothing into his or her mouth during that time.
The Baker test.
If the State cannot establish these foundational requirements, the breath test can be challenged and potentially excluded.
The Baker Rule: The 15-Minute Observation Period
Many Utah DUI attorneys refer to the “Baker rule” or “Baker observation period.”
Surprisingly, Baker was not originally a Utah case.
The rule comes from:
State v. Baker, 355 P.2d 806 (Wash. 1960) (en banc).
Utah later adopted the Baker framework through cases such as:
- State v. Vialpando, 2004 UT App 95;
- State v. Relyea, 2012 UT App 55; and now
- State v. Montgomery, 2026 UT App 77.
Why Mouth Checks Matter
The purpose of the observation period is scientific reliability.
Residual mouth alcohol can dramatically distort breath test results.
Things that can affect a breath test include:
- chewing tobacco,
- gum,
- alcohol residue,
- burping or regurgitation,
- vomiting,
- foreign objects,
- and other substances left in the mouth.
The Court explained in Montgomery that the purpose of the observation period is: “to allow any residual alcohol in the mouth to be absorbed into the system and to prevent the introduction of foreign matter into the mouth that could taint the results.”
State v. Montgomery: Utah Court of Appeals Reverses DUI Conviction
In State v. Montgomery, the defendant challenged the admissibility of his breath test because the officer:
- failed to perform a mouth check, and
- allegedly left the room during the observation period.
The Utah district court denied the motion and ruled the test admissible because:
- body camera footage existed,
- the interaction was recorded,
- and the court believed the defendant’s mouth appeared clear from the video.
The Court of Appeals reversed.
The appellate court held:
“We agree and hold that a mouth check is a foundational requirement for the admissibility of breath alcohol tests.”
That language is extremely important for Utah DUI defense cases.
The Court made clear that:
- an observation period alone is not enough,
- video review cannot replace a proper mouth inspection,
- and a breath test lacks proper foundation if officers fail to check the mouth before testing.
The Court further explained:
“All three criteria for the 15-minute observation requirement are necessarily undermined if the officer fails to establish that the suspect’s mouth is empty to begin with.”
That is now controlling Utah appellate authority.
Portable Breath Tests (PBTs) in Utah
Utah also regulates roadside portable breath tests under:
Utah Admin. Code R714-501
Portable breath tests are different from station-house evidentiary intoxilyzer tests.
Importantly:
- PBTs are voluntary,
- drivers may refuse them,
- and they cannot be the primary basis for arrest.
The rule also requires officers to:
- receive training,
- follow manufacturer standards,
- and properly document results.
DUI Cases Often Turn on Technical Violations
Many DUI prosecutions depend almost entirely on chemical testing evidence.
When breath testing procedures are flawed, the defense may challenge:
- admissibility,
- reliability,
- scientific validity,
- operator compliance,
- observation periods,
- machine calibration,
- or constitutional issues.
A chemical test is not automatically valid simply because a machine generated a number.
The State must prove the testing process was reliable.
That is exactly what Montgomery reinforces.
Charged With DUI in Utah?
If you are facing DUI charges in Utah, your case should be carefully reviewed for:
- breath test foundational defects,
- improper observation periods,
- mouth check violations,
- intoxilyzer calibration problems,
- officer certification issues,
- and constitutional violations.
At Provo Criminal Defense, we know how to challenge unreliable chemical testing and unlawful DUI investigations throughout Utah.
Learn More About Criminal Defense Lawyer Jake Gunter
For additional insights on Criminal Defense Law and to get to know Jake Gunter better, check out these helpful videos:
- Meet Jake Gunter – Learn more about Jake Gunter's background, experience, and dedication to helping clients throughout Utah.
- How to Choose a Utah Personal Injury Attorney – This video offers guidance on selecting the right personal injury attorney to ensure you receive effective representation.
- What Jake Gunter Does and Who He Represents – Discover the types of cases Jake Gunter handles and how he advocates for the rights of injured individuals statewide.
These resources will provide you with valuable information as you consider your legal options. For any questions or to schedule a free consultation, feel free to reach out to us directly