Breathalyzer Test Results Should Have Been Suppressed Based On Excessive Differential

June 30, 2014
By Parker Scheer LLP on June 30, 2014 11:37 AM |

Last month, the Massachusetts Appeals Court reversed the Boston Municipal Court's denial of a defendant's motion to suppress evidence of his post-arrest breathalyzer test as evidence of his alleged operation of a motor vehicle while under the influence of alcohol. The decision examined the regulations applicable to breathalyzer test results and their reliability.

In Commonwealth v. Hourican, the defendant had driven his vehicle into a police patrol wagon. Police observed that the defendant had "glassy eyes" and smelled of alcohol. After failing two out of three field sobriety tests, the defendant was arrested. He then consented to a breathalyzer test in which he produced two breath samples. One sample measured 0.121% blood alcohol content (BAC), and the other measured 0.143%, resulting in a differential between the two samples of 0.022%. Both samples indicated that the defendant's BAC level was above the legal limit of 0.08%.

The defendant moved to suppress the breathalyzer test evidence, arguing that the test was invalid based upon the 0.022% differential in the two breath samples. In support, he pointed to the Massachusetts Code of Regulations section 2.14(4), which provides that, if the administration of a breathalyzer test sequence "does not result in breath samples that are within +/- 0.02% blood alcohol content units, a new breath test sequence shall begin." The lower court denied the defendant's motion, reasoning that the regulation required that the differential of 0.022% be rounded down to 0.02%, because the regulation did not account for a third decimal place digit.

The Appeals Court reversed. In its analysis, it found support for the defendant's position, but also for the Commonwealth's argument that plain text of the regulation allows only for two decimal places. On balance, the Court ruled that the regulation was ambiguous, requiring it to be interpreted in favor of the defendant. A literal reading of the regulation and of the differential of the defendant's breath samples shows that the differential, 0.022%, was not mathematically within 0.02%. Thus, the officer should have conducted a new breath test sequence.

The Appeals Court also reasoned that this result was consistent with the practical considerations of the purpose of the regulation and fairness to criminal defendants. It noted that "the differential determines the underlying reliability of the instrumentation and process creating all test results," and "[a]n excessive differential casts doubt on the reliability of all the readings." Due to the weight that the breathalyzer test results carry when admitted into evidence against a defendant, there must be assurance of the reading's accuracy. Finally, the Appeals Court noted that the Secretary of the Executive Office of Public Safety and Security has the ability to cure the ambiguity in the regulation, and clarify whether a differential reading should be limited to two decimal places in all cases, whether rounding is permitted, or whether a three-decimal place differential should be considered in analyzing breathalyzer test readings.

Based upon this analysis, the Appeals Court reversed the denial of the defendant's motion to suppress the breath test results, thus excluding that evidence from being admitted against him at trial.