Prosecutors in Middlesex and Essex counties and on the Cape and Islands have suspended the use of breathalyzer tests until state police can effectively review whether the system is reliable.
Concerns about the test have led defense attorneys and prosecutors to sift through old cases for evidence of questionable breathalyzer results.
Executive Office of Public Safety and Security spokesman Felix Browne told WBUR that he cannot confirm how many cases are under review.
Martin Healy, the chief legal counsel at the Massachusetts Bar Association, told WBUR's Deborah Becker that he is calling for state Attorney General Maura Healey to take action.
"She should make the local district attorneys stop using the machinery until there's an independent investigation conducted by an outside investigator appointed by the AG, not the law enforcement," he said.
District attorneys say they learned about potential problems with the tests in mid-March. It's unclear how the state first became aware of the issue or the exact problem with the tests, and Browne says officials are also not certain there even is a problem with the tests.
But Healy said breathalyzer use has been a "long-standing problem."
"We've been questioning the use of these machines and the calibration of the machines for years," he said. "The machine itself is so unreliable in the minds of defense attorneys and in the minds of the legal community, because it can be thrown off by very minor readings, and they're very faulty when they've been tested by independent laboratories."
He said that citizens facing breathalyzer testing should — and legally are allowed to — demand to be taken to a local hospital to have their blood tested for alcohol there.
With reporting by the WBUR Newsroom and The Associated Press
This article was originally published on April 23, 2015.
This segment aired on April 23, 2015. The audio for this segment is not available.