Massachusetts prosecutors must stop using breathalyzer tests in most drunken driving cases. The ruling was handed down yesterday in a class-action lawsuit. It takes aim at what the judge terms “misconduct” at the Office of Alcohol Testing, which is a department of the Massachusetts State Police. Salem News court reporter Julie Manganis has been following the story for that paper. Manganis spoke with WGBH All Things Considered anchor Barbara Howard about the ruling. This transcript has been edited for clarity.

Barbara Howard: The breathalyzers have to be properly calibrated to be accurate, and you write that when they were bought, they were not calibrated properly by those responsible at the Office of Alcohol Testing, which is part of the Massachusetts State Police. Was the State Police forthcoming about this?

Julie Manganis: My understanding is that they weren't. Initially, they suggested that it was user error, basically putting the blame on the police officers and other people who were using the devices. So a group of lawyers ended up filing a class-action to try to get to the bottom of it.

Howard: When did it come out that these things weren't being calibrated properly?

Manganis: As I recall, an attorney in one drunk driving case had requested some data on the Draeger 9510 breathalyzer machines. They noticed some discrepancies. It kind of snowballed from there, and starting in March of 2015, several district attorneys decided that until they could resolve the issue, they would stop using the results in drunk driving cases.

Howard: What period of time are we talking about where the potentially faulty breathalyzer tests were given?

Manganis: This goes back to 2011 until now.

Howard: Had there been wrongful convictions due to breathalyzer tests?

Manganis: That's a question that really doesn't have an answer yet. The judge's decision does make way for defendants who might have pleaded guilty or been convicted to ask for new trials. But there is a caveat: They would have to show that they wouldn't have either pleaded guilty or gone to trial if not for the breathalyzer result, to say there wasn't other evidence against them, such as their performance on field sobriety tests. And that would be up to judges, case by case.

Howard: But for those who may have been convicted based on a breathalyzer test, which may now have been considered faulty, defense attorneys of accused drunken drivers are arguing that there could be huge amounts — tens of thousands of people — affected by this since 2011 with tainted cases, pointing out that that's even more than the number of the cases that were involved in the misconduct by the state chemist Annie Dookhan. Is that possible?

Manganis: It is. We don't know yet how many cases could have had a different outcome.

Howard: Does the lack of proper calibration mean that drivers were accused of being drunk when they were not drunk, or being let go when they were drunk? Any sense of that?

Manganis: That's hard to say. I don't think that was so much the issue. It was more about the evidence being used against them, and whether that evidence was reliable.

Howard: Who was it who brought on the class-action suit?

Manganis: There are several defendants in various parts of the state who were represented by counsel, and those attorneys got together. The lead attorney was a Springfield lawyer named Joseph Bernard. And he really kind of pushed this through.

Howard: It sounds like the hiding of this problem potentially by the State Police, folks who were overseeing the calibration, it wasn't to help one side or the other. It sounds like both prosecutors and the defense attorneys are not happy with this. Is that right?

Manganis: I think both sides are very upset about this and the outcome of the case. I think that is why the defense and the prosecution were able to reach an agreement last year on the exclusion of the breath test results going all the way back to 2011. I think both sides were surprised and disappointed at the extent to which the Office of Alcohol Testing and the State Police withheld evidence in the class action.

Howard: Well now, in order to start using the breathalyzer evidence again, the state has to get re-accredited, or at least demonstrate that's likely to happen. Explain that procedure. What happens next?

Manganis: Part of the agreement calls for the Office of Alcohol Testing to be accredited just like other testing labs. The majority of alcohol labs in the country are not necessarily certified, but as part of the process of correcting the issue, they have agreed to undergo this process, which could be fairly lengthy. The question was, how long do we wait to allow breathalyzer test results back into evidence? And that's where the judge's decision came down. He said they basically have to show that they're substantially under way toward getting accredited. We don't know yet when that will be.

Howard: Well now that the judge has ordered that the breathalyzer test not be used, at least for the time being, does that mean that drunk drivers who killed or maimed might be able to get off scot-free because these tests may have been compromised?

Manganis: No, because the judge carved out a few exceptions in his ruling for more serious cases, things like motor vehicle homicide while someone is driving under the influence, or people with fifth or subsequent offenses, serial drunk drivers.

Howard: That's Julie Manganis, court reporter for the Salem News. She has been following the story of breathalyzer tests in Massachusetts. A new ruling just out bans the use of breathalyzer results as evidence going forward due to questions about their accuracy. This is WGBH’s All Things Considered.

Correction: Due to a transcription error, an earlier version of this story incorrectly stated Annie Dookhan's first name. The post has been updated.