Breathalyzer Defense in Massachusetts

The breath test looks like the strongest evidence in an OUI case: a number, produced by a machine, wearing the authority of science. Massachusetts law treats it accordingly, and that is exactly why it is vulnerable, because the number is admissible only on top of a stack of statutes, regulations, certifications, and procedures, and every layer can be tested. This page covers the machine, the rules, the refusal questions, and the challenges. The roadside exercises that usually precede the test have their own page on field sobriety test defense.

The Machine Answers to the Regulations

A breath test result is admissible only on top of a stack of compliance. G.L. c. 90, § 24K requires a certified operator, an approved infrared device, and a test sequence of one breath sample, a calibration standard analysis, and a second breath sample. The regulations at 501 CMR 2.00 supply the details: the Office of Alcohol Testing must certify each device annually, the operator must hold a current certification, the operator must observe the driver for at least 15 minutes immediately before the test and restart the period if anything enters the mouth, the two breath samples must agree within 0.02, and the calibration standard analysis must read between 0.074 and 0.086. A result that cannot show its paperwork is a result a judge can exclude, and the certification records are discoverable. The science itself can be put to a hearing: Commonwealth v. Camblin, 471 Mass. 639 (2015), entitles a defendant to a reliability hearing on the machine’s methodology, and the follow-up decision, 478 Mass. 469 (2017), upheld the technology only after that scrutiny.

How the Machine Measures, and What That Leaves Open

The breath machine does not measure blood alcohol; it estimates it. Inside the device, infrared spectroscopy measures the energy ethanol molecules absorb in the breath sample, an electrochemical fuel cell independently measures the electrical current the alcohol generates, and the instrument compares the two readings, flagging the test when they diverge. The Supreme Judicial Court examined that technology in Commonwealth v. Camblin, 478 Mass. 469 (2017), after a defense challenge that reached the machine’s source code and its ability to distinguish ethanol from other compounds, and the court held the science reliable. Reliable science still rests on assumptions. The conversion from breath alcohol to blood alcohol applies a fixed ratio to every person even though the true ratio varies from person to person, the device pressed in Camblin carried no breath temperature sensor, and the safeguard against mouth alcohol comes down to the 15-minute observation period the regulations require. Those assumptions are why the compliance rules have teeth, and why the certification records, the observation period, and the two-sample agreement get read line by line in every case this office defends.

Refusals Never Reach the Jury

A driver may decline the breath test, and the jury will never learn it. G.L. c. 90, § 24(1)(e) provides that evidence that the defendant failed or refused to consent to a chemical test or analysis shall not be admissible against him. The Supreme Judicial Court reached the same result as a matter of constitutional law: refusal evidence is testimonial, and admitting it would force a driver to choose between producing evidence against himself and having the refusal used against him, a compulsion article 12 of the Declaration of Rights forbids. Opinion of the Justices, 412 Mass. 1201 (1992). The refusal still carries a Registry price, a consecutive suspension with no hardship relief while it runs, and the lengths are collected on our breathalyzer and license suspension page. Declining the roadside exercises is a separate decision with no license consequence at all, explained on our field sobriety test defense page.

A Change of Mind at the Station

Hesitation is common at booking, and the law sorts it into two clean outcomes. A driver who balks at first and then takes the test produces a result the Commonwealth may use if the regulations were followed, and the earlier hesitation stays out under § 24(1)(e). A driver who agrees and then fails to complete the sequence produces nothing usable, because a valid test requires two adequate breath samples that agree within the regulatory tolerance, and the Registry treats an incomplete effort as a refusal for suspension purposes. In both directions the trial rule holds: results come in when the paperwork supports them, and refusals never do. One caution belongs here: once a refusal is recorded, the police are not required to offer the test again, and the Registry suspension follows the recorded refusal.

The Office of Alcohol Testing Scandal

Compliance is not a technicality in Massachusetts, because the agency responsible for it spent years hiding its failures. In the consolidated Ananias litigation, the district court found that the Office of Alcohol Testing had withheld hundreds of failed calibration worksheets from defendants. In Commonwealth v. Hallinan, 491 Mass. 730 (2023), the Supreme Judicial Court attached a conclusive presumption of egregious governmental misconduct to the era: breath test results from Alcotest 9510 devices between June 1, 2011 and April 18, 2019 are presumptively excluded, and a driver who pleaded guilty in a case that included such a test may move to withdraw the plea. Convictions built on those numbers remain open to challenge today, and we review them on request.

The Records to Demand

Every breath test arrives with a paper trail, and the defense is entitled to it: the device’s annual certification, the calibration and periodic testing records, the operator’s certification, the documentation of the observation period, and the test record showing both breath readings and the calibration standard result. Gaps in that file become motions. A missing annual certification is an exclusion argument, an observation period that the booking video contradicts is an exclusion argument, and a calibration standard outside the 0.074 to 0.086 window invalidates the sequence outright. This office reads the file line by line in every breath test case, because the OAT era proved what paperwork can hide.

Challenge the Number

A breath test number is the beginning of the analysis, not the end of the case. Serpa Law Office defends OUI cases throughout Greater Boston, from the motion to exclude through trial, and advises on the Registry side while the criminal case runs. The common questions are answered in our breathalyzer FAQs and our Massachusetts OUI FAQs, the license consequences are on our guide to OUI license suspensions, the roadside exercises are covered on our field sobriety test defense page, and the broader framework is on our OUI defense page. Call 617.936.0201 for a free, confidential consultation.