Most Pennsylvania DUI (Driving Under the Influence) cases follow a predictable pattern: traffic stop, roadside field sobriety tests, an arrest, and finally a breath test at the police station to measure blood alcohol concentration.
While many assume that a breathalyzer reading is conclusive, Pennsylvania law imposes strict requirements on the administration and admissibility of these tests. Under Section 1547(c) of the Vehicle Code and 67 Pa. Code Chapter 77, compliance is mandatory. Failure to meet these standards can render the results inadmissible.
Here’s a breakdown of what every defendant (and their attorney) should know about the regulations in Chapter 77.
Foundational Requirements for Admissibility of Breath Tests (§ 77.24)
At a minimum, chemical breath tests must comply with six foundational requirements set forth in § 77.24:
- 20-Minute Observation Period
Before testing, the officer must observe you continuously for at least 20 minutes to ensure that you do not ingest or regurgitate anything prior to the breath test. § 77.24(a). While “observation” does not require the officer’s eyes to be on your mouth for every second, Commonwealth v. Snell, 811 A.2d 581, 586 (Pa. Super. 2002), police observation must be sufficient to establish that at least 20 minutes elapsed before breath testing commenced.
In Commonwealth v. Stoops, 723 A.2d 184 (Pa. Super. 1998), a police officer in Erie County testified that he conducted a traffic stop at 1:20 a.m. Id. at 189. The printout from the breathalyzer machine indicated that the first breath test happened at 1:37 a.m. Id. The Superior Court held that the suppression judge correctly excluded the breath test results because “the Commonwealth failed to overcome its burden of proving strict compliance with the regulations.” Id.
- Two Consecutive Breath Tests
The officer then must administer two consecutive breath tests, § 77.24(b)(1), and only the lower of the two results may be used in court, § 77.24(b)(2). This requirement is not a technicality—it is a fundamental safeguard built into Pennsylvania’s breath-testing regulations. The back-to-back tests help protect against an anomalous machine reading.
Pennsylvania courts have enforced this rule strictly. In Commonwealth v. Diulus, 571 A.2d 418 (Pa. Super. 1990), the Commonwealth attempted to rely on a single breath reading, even after the arresting officer acknowledged that only one sample had been tested. Id. at 419. The Superior Court held that the breath test was invalid given the lack of consecutive test results. Id. at 420.
Diulus reinforces a key principle: if two valid consecutive breath samples are not obtained, the breath test fails as a matter of law and should be suppressed.
- Consistent Results
To be valid, section 77.24(b)(2)(i) requires the two consecutive breath samples to fall within acceptable tolerances:
- For machines reading to two-decimal places, results must be within 0.02
- For machines reading to three-decimal places, results must be within 0.020
The case of Commonwealth v. Mabrey, 594 A.2d 700 (Pa. Super. 1991), is instructive on this requirement. In Mabrey, the Commonwealth sought to introduce breath test results from a device that, on seven occasions since its last calibration, had failed to produce two consecutive breath samples within the acceptable tolerances required by § 77.24(b)(2)(i). Id. at 701. Despite these out-of-tolerance readings, the machine was never taken out of service or recalibrated. Id.
The Superior Court affirmed suppression of the defendant’s breath-test results, holding that the device’s prior deviations demonstrated noncompliance with the regulatory framework governing admissibility. Because the machine should have been removed from service and recalibrated before further use, the results obtained from it were inadmissible. Id. at 703.
- Immediate Simulator Test Afterwards
Right after the second breath test, the operator must run a simulator test using a certified solution designed to read 0.10%. § 77.24(b)(2). This confirms the machine was functioning properly at the exact moment of your test. If the simulator test was omitted or produced a result yielding “less than .09% or greater than .10% when the breath test device is read to the second decimal place, or if the simulator test yields a result less than .090% or greater than .109% when the breath test device can be read to the third decimal place,” the BAC (Blood Alcohol Concentration) results can be challenged. § 77.24(b)(2)(ii).
- Certified Simulator Solution
The simulator solution used during the control test must be certified by the manufacturer, and that certification must confirm the alcohol concentration through independent gas chromatographic testing. § 77.24(d). If the Commonwealth cannot establish that the simulator solution was properly produced and independently verified, the reliability of the entire breath test can be called into question.
Pennsylvania courts have treated this requirement as essential. In Commonwealth v. Thill, 612 A.2d 1043 (Pa. Super. 1992), the prosecution used a simulator solution that had been both produced and tested in separate divisions of the same laboratory. Id. at 1045. The Thill Court held that because the simulator solution was not produced and tested in independent laboratories, the breath test results were inadmissible at trial. Id. at 1047.
- Certified Operator
The officer must be certified to operate that specific breath testing device. § 77.24(b). If not, the results may be excluded.
Accuracy Inspection (§ 77.25)
Every breath testing device that produces chemical breath tests for use in court must be approved by the Pennsylvania Department of Health. 75 Pa.C.S. § 1547(c)(1). In addition, the device must pass two separate maintenance checks to remain in service.
The first maintenance check requires the machine to undergo an “accuracy inspection test” within 30 days before your breath test. § 77.25(a). If this inspection wasn’t completed in time, the results are not considered reliable.
The accuracy inspection entails five individual tests with a simulator solution manufactured to produce a 0.10% reading. § 77.25(b)(1)(iii). Section 77.25(b)(2) provides that the machine must come out of service if:
- For machines reading to two-decimal places, any result falls outside 0.09–0.10%
- For machines reading to three-decimal places, any result is outside 0.090–0.109%, or the average deviation of all five results exceeds 0.005
The results from the accuracy inspection test must be documented in a signed certificate that must be retained for three years. § 77.25(c).
Annual Calibration (§ 77.26)
The machine must undergo a second maintenance check called a “calibration test” within 365 days prior to your breath test. § 77.26(a). The calibration test is like the accuracy inspection test except that it uses three simulator solutions: 0.05%, 0.10%, and one higher solution that is a multiple of 0.05%. § 77.26(b)(1). Five individual tests are conducted at each level. According to section 77.26(b)(4), a failure occurs when:
- Two-decimal machines: any value is more than 0.01 above or below the target
- Three-decimal machines: any test is more than 0.010 too low or 0.009 too high, or the average deviation exceeds 0.005
Like the accuracy inspection test, the calibration test results must be enshrined in a signed certificate that is kept for three years. § 77.26(d).
Why This Matters in Your DUI Case
Breath test results aren’t automatically accurate—or admissible—just because they come from a machine. Skilled DUI attorneys routinely expose errors, omissions, and regulatory violations that can undermine or completely exclude a BAC result.
If you are facing a DUI charge, understanding these requirements is critical. Reach out to Bart Wischnowski at (412) 594-5565 or bwischnowski@tuckerlaw.com to review the breath test in your DUI case and protect your rights.