Ghost guns that were secured by the D.C. police are displayed during a news conference held by Mayor Muriel E. Bowser in February 2020. (Astrid Riecken for The Washington Post)

The D.C. Council voted Tuesday to amend the city’s law that bans untraceable firearms, also known as “ghost guns,” in response to a federal lawsuit that alleged the law was overly broad.

The lawsuit was filed in September by a group of plaintiffs including Dick A. Heller, who successfully challenged the city’s ban on handguns in the landmark 2008 Supreme Court decision District of Columbia v. Heller. He now asserts that the District’s ban on ghost guns, passed last year, unjustly outlaws all polymer-based guns — including Glock handguns, which are issued to many D.C. police officers. (Military and law enforcement agencies are exempt from the ban.)

In the suit, Heller asserted that the city’s prohibition on manufacturing guns prevented him from building his own firearm from a kit, even though he was willing to register it and place a serial number on it. Homemade polymer guns are called ghost guns because they don’t have a serial number, and purchasers are not required to undergo a background check. Officials have said the prevalence of these guns has contributed to rising levels of violence.

But on Tuesday, the D.C. Council took emergency action that officials hope will mitigate the issues laid out in the suit. Introduced by D.C. Attorney General Karl A. Racine (D), the changes seek to ensure that only undetectable firearms are captured in the city’s definition of “ghost gun.”

The current law defines a ghost gun as one that will not set off a metal detector after all parts are removed other than the receiver. But that can leave only a polymer frame, the lawsuit stated, adding, “The District has apparently unwittingly made … existing polymer frame handguns illegal.” Under the change approved Tuesday, guns would have to be detectable with their barrel, trigger and firing mechanism attached, even if the receiver is polymer-based, to prevent construction of a completely plastic gun.

The amended language also outlines a process for legally possessing self-manufactured firearms: The guns cannot meet the new definition of ghost guns, they must be lawfully registered and solely for personal use, and they must have unique serial numbers.

George L. Lyon Jr., Heller’s lawyer, said the council’s actions Tuesday appeared to be a first step toward addressing the issues in the lawsuit and more closely aligning the city’s definition of ghost guns with federal statutes.

D.C.’s ghost-gun law faces legal challenge from Dick Heller, successful gun rights activist

“If this does ultimately become law, then it does address my concerns. It appears they are trying to fix the problems,” Lyon said.

He added that he still has a request for a preliminary injunction pending, and that because the changes were approved on a temporary basis, an additional legislative process is needed for permanent change.

The legislation was approved 12-to-1 and now heads to Mayor Muriel E. Bowser (D) for consideration. Council member Brooke Pinto (D-Ward 2) was the only vote against the measure. She argued that “the proliferation of ghost guns in our city is certainly not what the founders anticipated or intended,” even if it is subject to legal challenge.

“I’m hoping for more clarification on why we as a city have to continue allowing something that in my view is extremely outside the scope of what the founders intended,” she added.

Tom Jackman contributed to this report.