BURLINGTON, Vt. —The estate of an unarmed man who died after being shocked by a state police stun gun filed a federal lawsuit Wednesday as a way to hold police accountable for their actions, an attorney said.

The lawsuit, filed in U.S. District Court in Burlington, maintains police used excessive force when they responded to Macadam Mason’s Thetford home on June 20, 2012, after they were asked to check on his well-being by an official at the Dartmouth Hitchcock Medical Center in Lebanon.

Attorney Robert Appel was accompanied to federal court by Mason’s mother, Rhonda Taylor; her husband, Ken Taylor; and Allen Gilbert, of the Vermont chapter of the American Civil Liberties Union.

“I have to say this is a very sad day, not only for Rhonda and her family but for the state of Vermont,” Appel said. “This is the only way the people of this state can hold police accountable.”

The lawsuit seeks unspecified damages, which would benefit Mason’s daughter, Appel said.

State police spokeswoman Stephanie Dasaro said Wednesday it would be inappropriate to comment on pending civil litigation.

Mason’s death after being shocked in the chest by an electronic stun gun outside his home prompted the Legislature to pass a law requiring the creation of a stun gun use policy that will be adopted by police departments. The law also says officers may use stun guns only against people who are exhibiting active aggression or who are actively resisting in ways likely to harm themselves or others.

Mason was suffering from what records call a mental health crisis.