A Massachusetts Supreme Judicial Court judge has determined that just because a motorist appears to be stoned doesn’t mean they have been operating a vehicle under the influence of marijuana.

Central District Court Judge Andrew M. D’Angelo said last week during an evidentiary hearing that while he acknowledges the consumption of marijuana can lead to impairment, there is “no evidence” that characteristics such as “red eyes and drowsiness” are “equated with impaired driving.”

D’Angelo went on to say that a police officer could not measure how a person’s marijuana use has hindered his or her ability to drive.

To come to this conclusion, D’Angelo referenced a number of previous studies that found most people under the influence of THC, the psychoactive compound of the cannabis plant, have no problem passing field sobriety tests. In fact, one of the studies used in making this determination showed that 50 percent of occasional marijuana smokers passed Standardized Field Sobriety Tests (SFST) with flying colors.

Last week, voters in Massachusetts passed an initiative (Question 4) that legalized marijuana throughout the state in a manner similar to alcohol. However, opponents of the measure have expressed concern that legal weed will lead to more cases of stoned driving, therefore posing a threat to the well-being of civil society. Some of the state’s police forces have even said that they plan to start targeting stoned motorists the same way they do with drunk drivers.

But Judge D’Angeleo says this approach simply will not work—giving those people busted for driving high in Massachusetts a fighting chance at defending their cases in court.

“An OUI Marijuana charge is a very winnable case, because typically the Commonwealth will have no evidence as to how much you smoked, when you smoked marijuana and will lack an expert to say what impact any marijuana intake would have on your ability to drive,” Massachusetts DUI defense attorney Michael Delsignore wrote in a recent blog.

Interestingly, prosecutors in other legal marijuana states are apparently having a difficult time nailing down convictions when it comes to stoned driving cases—that is as long as the defendant refuses the plea deal and takes his or her case to trial.

Earlier this year, it took a Colorado jury only a matter of 30 minutes to deliver a “not guilty” verdict on a man accused of driving high. In the end, the jurors said there just wasn’t enough evidence to prove Ralph Banks, who tested almost three points over the legal limit during a blood test, was technically impaired when he was stopped for a missing headlight in 2015.

Some of Colorado’s leading legal eagles have confirmed that almost all stoned driving cases that go to trial end in acquittal.

Jefferson County District Attorney Peter Weir told CBS News in March: “These are difficult cases to prosecute” because “our current law is not strong enough to effectively hold people accountable.”

It is now up to the Supreme Judicial Court to decide whether to stand in favor of Judge D’Angelo’s decision. The court is expected to begin hearing arguments on this matter at the beginning of 2017. There is speculation that this ruling could change the procedures police forces all across the state of Massachusetts are presently using to determine marijuana impairment.

You can keep up with all of HIGH TIMES’ marijuana news right here.