Nothing prevented Brian Kennedy from walking into a gun shop last month and buying an AR-15, the semiautomatic weapon he would use to kill his ex-wife days later at a Radnor Wawa store. But if Pennsylvania had “red flag” protection, lawmakers said Friday, the Devon man might not have been able to make that purchase and use the gun to take the life of Stephanie Miller.

In the wake of the killing, Delaware County District Attorney Katayoun M. Copeland joined legislators and gun-control supporters outside the courthouse in Media on Friday to push for a law that would allow relatives and law enforcement officers to ask a judge to temporarily disarm those who pose a threat to themselves or others.

“We don’t know, in every situation, what could work," said Shira Goodman, executive director of CeaseFirePA. “But we know this has worked in other states.”

The measure, known as an extreme risk protection order (ERPO) law, is in place in 13 states, including New Jersey and Delaware. In some states, suicide rates have dropped since the legislation was enacted. ERPO supporters say it could prevent mass shootings, too. Critics say the law denies due process and overlooks the importance of mental-health treatment.

State Rep. Todd Stephens (R., Montgomery) and Sen. Tom Killion (R., Delaware) say it’s time that Pennsylvania offers this option. They’re sponsoring bills in the House and the Senate, hoping ERPO will gain more traction than it did last session.

The bill allows people to repossess their guns after a crisis has passed, Stephens said, and offers families an alternative to involuntarily committing their loved one to a mental health treatment facility. An involuntary commitment, he noted, comes with a lifetime restriction on gun ownership, while ERPO’s prohibition is temporary.

After an initial ERPO is granted, with “necessary evidence,” the court must hold a hearing within 10 days. The gun owner may be represented by an attorney, call witnesses, and introduce evidence in a bid to have the order overturned. If the judge upholds the order, it could be extended for three months to a year.

“Necessary evidence” could include domestic abuse, threatening behavior, and the recent purchase of a gun combined with other concerning behaviors, Copeland said.

Miller got a protection-from-abuse order against Kennedy after he threatened her life at the same Wawa in 2016, but the order lapsed in September.

Could a “red flag” law have saved Miller? Maybe not, Copeland said: “One doesn’t know whether this would have made a difference at the end of the day.” Still, she said, she’s hopeful the measure could prevent other deaths.