Breathalyzer accuracy questioned by defense attorneys

More than 60 defendants from Middlesex, Hampden, and Essex Counties have joined together to argue that the breathalyzer machine used in Massachusetts to determine whether an operator is under the influence of alcohol is unreliable.

The case, Commonwealth v. Daens, is scheduled to begin on March 1st in Worcester District Court pending the courts review of Middlesex District Attorney Gerard Leone’s motion to deny the hearing.

“I don’t know of any other criminal proceeding that advances on a piece of paper that can tell you if you are guilty or not guilty, and the commonwealth doesn’t have to present a live person to admit the paper into evidence,” Lynda Lee Dantas of the Committee for Public Counsel Services told Massachusetts Lawyers Weekly. Dantas is also encouraging other defense lawyers with OUI clients to file motions to exclude breath-test results as unreliable evidence in their pending cases.

At issue is the reliability of the Alcotest 7110, which is used to determine whether a drunk-driving suspect has a blood-alcohol level above .08 percent, the legal limit for driving in most states. The machine relies on a microprocessor with approximately 60,000 lines of source code to interpret the breath-test results, according to Thomas E. Workman Jr., a Taunton lawyer and computer forensics expert witness working with the defense in Daens.

The device uses infrared and electrochemical measurement systems to analyze the person’s breath and determine the amount of alcohol present in his body.

A similar argument was raised in New Jersey and was heard there by the New Jersey Supreme Court. The court found in State v. Chun, et al. that the Alcotest’s source code was reliable and allowed police agencies in the state to continue using the machine.

The court did raise several concerns over the device, however, it determined that only one issue, a “buffer overflow error,” could potentially skew breath-test results. The error has been resolved in Massachusetts, according to Leone’s motion to deny the hearing.

“In any event, the New Jersey Supreme Court has already considered and squarely rejected the defendants’ claims regarding the relationship of alleged flaws in the source code to the reliability of the Alcotest,” Leone states. “This Court should adopt the Court’s findings in Chun and reject the defendants’ arguments on the merits.”


About Attorney John J. MacLaughlan

John MacLaughlan is Massachusetts licensed attorney as well as a Boston police officer. John is currently assigned to the Youth Violence Strike Force (Gang Unit). He is a graduate of the Massachusetts School of Law with a concentration in Labor Law. He holds a Master’s Degree in Criminal Justice from the University of Massachusetts at Lowell as well as a Bachelors Degree in Political Science from the University of Massachusetts at Amherst. John has taught Defensive Tactics, Firearms, Use of Force, Applied Patrol Procedures, and Police Response to Active Shooters to sworn police officers and police academy recruits. Prior to becoming a Boston Police Officer, John served for 9 years as a police officer in Lowell, where he was a member of the Police Dive Team and Patrol Rifle Team.
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One Response to Breathalyzer accuracy questioned by defense attorneys

  1. Just Nobody says:

    I am continually amused when Legal eagles attempt use “geek speak” in legal arguments. If a device EVER has one buffer overflow, it is 99.999% probable that there is another one waiting to surface. Like Radar and Lidar, it is sofware and hardware that was created by humans and will always be subject to failure. The breathalizer as a portion of evidence can be arguably reasonable; however, conviction often hinges on the breathalizer.

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