A New Jersey Supreme Court decision could cause more than 20,000 drunken driving convictions to be vacated.

In their unanimous decision issued Tuesday, the justices found that criminal charges against a state police sergeant who was in charge of calibrating breath-testing devices made the test results from five counties inadmissible as evidence.

The decision means that as many as 20,667 DWI convictions could now be challenged.

Authorities have alleged that Sgt. Marc Dennis skipped a required step in the calibration of the devices. He has denied any wrongdoing and has pleaded not guilty to records tampering and other charges.

The accusations called into question any test result involving a machine he handled, including devices used by local police in Middlesex, Monmouth, Ocean, Somerset, and Union counties between 2008 and 2016.

The ruling was based on a case brought by Eatontown attorney Michael Hobbie in 2016 for his client Eileen Cassidey. Cassidey pleaded guilty to drunk driving based on a breathalyzer test linked to Sgt. Dennis.

“If we would have known about it, she never would have pleaded guilty,” Hobbie says.

Cassidey died from an unrelated illness this past March. But with the court’s ruling, her conviction was vacated.

“The bigger issue is for people going back who pleaded guilty,” Hobbie says. “They paid their fine, they’ve had their license suspension, maybe had the interlock device and in some cases maybe served jail time. What do they do?”

New Jersey Attorney General Gurbir Grewal says that his office is still working out what will happen to some of the people who were convicted based on the tests.

“We’re still processing it and we’re still coming up with guidance for our county prosecutors and municipal prosecutors who handled many of these cases,” he says.

Hobbie urges anyone who may be impacted by the situation to seek legal advice about how to proceed.