“When properly used and maintained, the breath test instrument is one of the most accurate and reliable tools we have to identify and investigate drunk drivers,” Felix Browne, spokesman for the Executive Office of Public Safety and Security, said in a statement. “To ensure the integrity of this method of testing, which is used by departments across the Commonwealth, the State Police are performing a review to determine whether any problems exist in the testing procedures.”

Concerns about the test, which prosecutors were informed of last month, have led defense attorneys and prosecutors to sift through old cases and look for evidence of questionable breathalyzer results.

Prosecutors in Middlesex and Essex counties and on the Cape and Islands have suspended the use of breathalyzer test results in drunk-driving cases until State Police complete a review of whether the test procedure is reliable, authorities said Wednesday.


Browne said Wednesday he was unable to confirm how many cases might be affected by the ongoing review. An official with knowledge of the review said state authorities believe about 69 cases are involved, out of about 6,000 tests conducted throughout the state with the device, which measures the level of alcohol in the blood. The review could confirm that number of cases or modify it.

Browne declined to elaborate on what might be wrong with the tests, saying in an e-mail that “it has not been determined that there is one.” He did not respond to a question about how the issue was detected, and did not have information about when it began.

Middlesex District Attorney Marian T. Ryan said in an interview that the issue involved machine calibration, and that she ordered her staff Wednesday to immediately stop offering breathalyzer test results in cases.

“I’m really doing it in an abundance of caution, because we just don’t know yet,” Ryan said. “Obviously, as prosecutors, we’re always concerned about the integrity of the evidence we submit to the courts.”


Ryan said fewer than a dozen cases in Middlesex County have been identified as possibly being affected, and her office is looking through files and notifying defense attorneys.

In Essex County, five cases dating to late 2011 have so far been identified as possibly being affected, said Carrie Kimball-Monahan, spokeswoman for District Attorney Jonathan Blodgett.

“It is premature to speculate as to the possible impact this review will have on current or previous cases,” Kimball-Monahan said in a statement. Echoing Ryan, she said the decision to stop using breathalyzer results was made “in an abundance of caution.”

The Essex DA was notified in mid-March by State Police about a possible issue with breathalyzers, she said. On April 15, State Police representatives told the Massachusetts District Attorneys Association that a review was underway “to determine the exact nature and scope of the issue,” Kimball-Monahan said.

Cape and Islands District Attorney Michael O’Keefe said in a statement that “I have instructed our assistant district attorneys to refrain from introducing the breath test in any case and to so inform defense counsel until we receive further information from the Executive Office of Public Safety.”

Attorney Armond C. Colombo Jr., who represents a defendant who pleaded guilty to a 2013 drunk-driving charge, said he will be looking through all of his old operating-under-the-influence cases.

“My client may have made an admission, based on this new evidence, that he would have the right to withdraw,” Colombo said. “It’s probably evidence that now would be inadmissable.”


In Norfolk County, eight cases dating to 2013 were identified as being affected, according to David Traub, spokesman for Norfolk District Attorney Michael W. Morrissey.

Four are pending, he said, and the breathalyzer results will not be used.

Three cases resulted in guilty pleas, and defense attorneys are working with their clients to decide how to move forward, Traub said. The final case resulted in conviction at trial, he said, but prosecutors withdrew the case and the verdict was vacated.

Traub said prosecutors in Norfolk “have not been given reason to believe that the number will expand [past eight cases] unless there’s an error made on a future arrest.”

Norfolk will not stop using breathalyzer results, he said.

“When properly calibrated, the results are valid and admissible,” he said.

Only two affected cases have been discovered in Suffolk County, said Jake Wark, spokesman for District Attorney Daniel F. Conley.

Worcester County is reviewing its use of breathalyzers, said a spokesman, who declined to comment further.

Randy Gioia, deputy chief counsel for the Public Defender Division of the Committee for Public Counsel Services, which provides legal representation for people who cannot afford a lawyer, said all district attorneys should not use breathalyzer test results until the review is complete.

Gioia said state officials and prosecutors appeared to be responding appropriately and responsibly, but said the review must be speedy.


“There may be some people who have been convicted based on faulty breathalyzer results who shouldn’t have been, who shouldn’t be on probation, or shouldn’t have lost their driver’s license,” he said. “It could be affecting people right now.”

Evan Allen can be reached at evan.allen@globe.com. Follow her on Twitter @evanmallen. Travis Andersen of the Globe staff contributed to this report.