Lebedevitch did not return a call seeking comment.

Sinnott rejected a Police Department motion to reconsider the case, finding that legal precedents the department cited to justify the license rejection are no longer valid under the Bruen ruling. In a brief, handwritten decision, he ruled that the Bruen case effectively removed Cox’s discretion in determining Lebedevitch’s suitability for the license.

“The ‘unsuitability standard’ is [the same as the] ‘may issue’ discretion rejected by Bruen,” Sinnott wrote.

Following the Bruen ruling, state authorities issued guidance to police departments in Massachusetts saying they could still enforce portions of the law that deny gun rights to convicted felons and that give police chiefs the power to reject licenses for “unsuitable” applicants who could pose a risk to public safety if armed.

But if applied statewide, Sinnott’s ruling could upend that remaining authority.

And it is not the first time a Massachusetts resident has used the Bruen ruling to successfully overturn the denial of a concealed carry license. In May, Holyoke District Court Judge William Hadley ordered the city’s police department to grant a license to a man it had deemed unsuitable because of years-old drug and domestic violence allegations. Hadley ruled that while states may restrict licenses from people who would likely be dangerous if armed, Massachusetts’ current standard is too broad — requiring only “a suggestion, a hint, or an insinuation that there may be danger.”

In July, Holyoke city officials challenged Hadley’s decision in a lawsuit in Hampden Superior Court. That case is still pending.

Lawrence Friedman, a professor of constitutional law at New England Law, said the Boston case could have significant implications for both the law and public safety.

“The city probably has a strong interest in making sure they can take weapons away from people who the police believe will do themselves harm,” Friedman said.

Friedman said the Supreme Court’s ruling that gun laws must respect the “historical tradition of firearm regulation” in the United States has created uncertainty across the country, with a raft of legal challenges to gun laws that remain undecided. In June, the Supreme Court also upheld a federal law barring people under domestic violence restraining orders from possessing guns.

The court has been quite circumspect about what the full reach of the Second Amendment actually is,” Friedman said. “We just don’t know until more cases are decided.”

Of the Boston case, he added, “If this ultimately gets appealed all the way up to the [state] Supreme Judicial Court, it could be a very significant ruling either way.”

Michael Ulrich, an associate professor of health law at Boston University who has studied the effects of firearm policy,said local judges such as Sinnott are responsible for incorporating new Supreme Court case law in their decisions, even if that means breaking legal ground at the state level. But he said it is unusual for such a potentially sweeping decision to have so little formal justification behind it.

“It’s a bit surprising to have it being done at this level, but also in a handwritten note,” Ulrich said in an interview. “A constitutional analysis takes time and consideration and thoughtful explanation as to the outcome.”

Sinnott’s decision was not his first judicial face-off with local law enforcement. In 2019, he refused to allow Suffolk County prosecutors to drop charges against protesters who clashed with police following a “Straight Pride” parade in Boston. He had a defense attorney who argued with his decision handcuffed and held in custody for three hours. An SJC justice eventually ruled in favor of then-district attorney Rachael Rollins, finding that Sinnott had no authority to stop prosecutors from dropping one of those cases.

Weeks later, theMassachusetts Commission on Judicial Conduct launched an investigation into Sinnott’s handling of the cases, but has since provided no public information about its inquiry. Complaints against judges remain confidential unless a judge has agreed to a public disclosure, when the commission files charges against a judge with the SJC , or when the SJC imposes a public disposition, according to the commission’s website.

Sinnott has personal experience with Second Amendment protections. In 1980, he shot and wounded 22-year-old Coast Guardsman Michael Hulme on City Hall Plaza after Hulme and four other men allegedly attacked him. Suffolk prosecutors said at the time that Sinnott acted in self defense.