How a temporary restraining order for guns could help stop mass shootings An Extreme Risk Protection Order is a temporary restraining order for guns.

 -- One relatively unknown tool for stopping gun violence may soon get a lot more attention.

An Extreme Risk Protection Order (ERPO) empowers family members and police to take guns away from a person who may pose a danger to themselves or others. The person's access to firearms is blocked until they can demonstrate that the risk is over. Essentially, ERPOs are a temporary restraining order for guns.

As of now, only Washington, California, Connecticut and most recently Oregon have ERPO laws (while Indiana and Texas have modified risk warrant statutes). Over the past year, however, spurred by a string of mass shootings beginning with the Pulse Nightclub attack that killed 49 in June 2016, legislatures in 19 states and Washington, D.C., have taken up 32 separate ERPO bills for consideration, according to Everytown for Gun Safety, a nonprofit organization that advocates for gun control.

Everytown’s deputy legal director, William Rosen, told ABC News that list will grow. “We expect to see at least as much interest in 2018,” he said.

“There is a growing consensus that this is the first step we should be taking when we are talking about people who are at risk of hurting themselves or others,” according to Lauren Alfred of the gun violence prevention group Sandy Hook Promise.

Current laws barring gun ownership are limited. Generally, a person with a long history of mental health issues can still legally buy or possess firearms if they don’t fall into specific statutory categories such as having been adjudicated mentally ill or under a domestic violence restraining order. But, as was the case with Texas church gunman Devin Kelley, even these restrictions may not work if the person’s troubled past is not recorded on a background registry.

With an ERPO, however, if family members or police can show a gun owner to be an imminent danger to themselves or others, they can force the person to surrender their weapon(s).

Mass murderers like Aaron Alexis who killed 12 at the Washington Navy Yard or Elliot Rodger who slaughtered six in Isla Vista, California, are cited by experts as people who might have been halted by ERPOs.

"Those were both cases where law enforcement believed those shooters might be a threat to their workplaces or people they knew,” said Alfred. “But law enforcement felt like their hands were tied."

Where ERPOs are believed to be most often effective is in stemming suicides. For example, Everytown cites a study of the law in Connecticut (where it has been in place the longest) that states that from 1999 to 2013, “For every 10 or 11 gun removal cases, one suicide was averted -- an estimated 72 averted suicides.”

While there is a clear spike in the number of states considering ERPOs, efforts to implement these laws have faced significant resistance from those who want to protect constitutional rights to gun ownership.

As Oregon’s state legislature was considering its ERPO law this summer, the National Rifle Association said in a statement that the bill “would allow people who are not mental health professionals, who may be mistaken, and who may only have minimal contact with the respondent to file a petition with the court and testify on the respondent’s state of mind.”

The ERPO “strips the accused of their Second Amendment rights [and] would be issued by a judge based on the brief statement of the petitioner,” the NRA's statement added.

The answer to such concerns embedded in these laws is that courts must show “substantial evidence” that a person is a risk to themselves or to others. In addition, the removal of the firearm is only temporary (generally a year) unless the ERPO is renewed in a later hearing. These measures, said Alfred, have "overcome a lot the Second Amendment legal and political concerns."

While it is impossible to determine how many of the recent shooting tragedies ERPOs could have prevented, they could have provided at least “another layer of protection,” said Rosen. “Mass shooters often display warning signs before they carry out their attacks, and ERPO provides an opportunity for family members or law enforcement to intervene before a tragedy occurs.”