In recent years, Massachusetts' criminal justice system has been rocked by two scandals surrounding the test samples of narcotics used to convict thousands of people for various drug offenses. In Jamaica Plain, Annie Dookhan fabricated test results, and in Amherst, Sonja Farak consistently stole samples of the substances she was supposed to test. Both of these incidents led to thousands of overturned cases and the restructuring of how the state handles test samples.

But a larger scandal is looming, one that could affect roughly 35,000 drunk driving cases across the state. For years, police departments used breathalyzers that were improperly calibrated, meaning the results of breathalyzer tests could be inaccurate. This opens a window for defense attorneys to argue convictions should be overturned. To put the case in context and understand its potential consequences, WGBH's Morning Edition Anchor Joe Mathieu spoke with legal analyst and Northeastern Law Professor Daniel Medwed. The transcript below has been edited for clarity.

Joe Mathieu: First of all, tell us about the problems with the breathalyzer test itself. What went wrong?

Daniel Medwed: Well, the scandal revolves around the office of alcohol testing, which is an arm of our state crime lab and monitors are breathalyzers, which, of course, are the devices used by officers typically at the scene of a suspected drunk driving incident to test whether or not the motorist has a legally significant amount of alcohol in his or her bloodstream. Apparently, for a number of years, the office failed to properly calibrate these devices and compounded that error by not disclosing these failures to either the defense or the prosecution. What that means is that the integrity, the accuracy of all of those affected tests remains in doubt.

Mathieu: This was on a wide scale, Daniel. How many cases are we talking about here?

Medwed: Well, I've heard numbers north of 35,000 affected cases, or at least tests. Defense lawyers have brokered a tentative deal. It has to be subject to judicial approval, with our 11 county district attorneys in the Commonwealth. That would mean that people affected by these problematic tests could get a retrial, in which the breathalyzer results could not be reintroduced into evidence. Now, that doesn't mean that we're going to have 35,000 new trials. For one thing, many of those tests were redundant. The same person did multiple breathalyzer tests, or the breathalyzer was used for something other than a suspected drunk driving incident. Also under the terms of this deal, certain very serious offenses like vehicular homicide involving driving while impaired would be exempt from the retrial issue. But nevertheless, there could be thousands and thousands of cases overturned and potentially subject to retrial.

Mathieu: We're talking with WGBH News legal analyst, Northeastern law professor Daniel Medwed about the breathalyzer scandal involving the state office of alcohol testing. So, what does this mean for these cases? Can they be retried, Daniel, and if so, how could the prosecution win without the test results?

Medwed: Those are great questions. I think some will be retried, and some will actually result in convictions again because there is extraneous information about intoxication. Let's say there were failed field sobriety tests, or simply observations of drunken behavior, or perhaps a confession by the motorist. Some of the cases might result in plea bargains, but I do think some of them will result in acquittals or might be dismissed because of insufficient evidence without those breathalyzer test results. And that's probably the right result, because the office of alcohol testing failed to act responsibly. It might be a steep price to pay, but I think it's a legitimate one.

Mathieu: These make tough headlines, Daniel, given the crime lab scandals in J.P. and Amherst that I mentioned. Now, this, what do we need to do, if we can do anything to restore trust in our agencies that oversee evidence testing?

Medwed: A couple thoughts. First, in terms of the office of alcohol testing, most units within the state crime lab are subject to national accreditation processes. This office historically has not been subject to those processes. Our executive office of public safety has basically demanded that the office go through it. So that reform is in the works and will be a step forward. Second, on a global level, when you take all of these scandals together, a very powerful theme emerges — the lack of transparency and accountability over our state crime lab and the units within it. So potential reform could be to create a robust independent commission, let's say of X judges, X prosecutors, X defense lawyers. Maybe they could have random audit power, to go into these units and conduct tests randomly. At the very least, that would keep the state crime lab on its toes.

Mathieu: This is why we talk to Daniel Medwed, WGBH News legal analyst, Northeastern law professor. We have this conversation every week on WGBH's Morning Edition. Thanks again, Daniel.