Police used the Red Flag Law to seize the weapons of Brandon Wagshol, a Connecticut man accused of expressing interest in committing a mass shooting.

The law exists because of a mass shooting authorities couldn't prevent.  On March 6, 1998, an angry accountant opened fire at the Connecticut Lottery headquarters. Four of his bosses were killed. The shooting led Connecticut to pass the nation's first-ever "Red Flag Law."

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"We didn't have a red flag law -- that never existed.  Had that been in place that lottery shooting could have been avoided," says state Sen. Bob Duff (D-Norwalk).

Under the law, a judge can temporarily take away someone's weapons if they're a danger to others or even themselves. A Yale study found Connecticut's Red Flag Law has prevented 72 suicides. In all, judges have used it more than 1,200 times.

After this month's mass shootings in Ohio and Texas, Congress may consider a national Red Flag Law.

"We are closer than ever to real action that can save as many lives as possible, as quickly as possible," says Sen. Richard Blumenthal (D).

Connecticut's Red Flag Law also protects domestic abuse vicitms.

"The applications to domestic violence can't be understated," says Diane Dauplaise, a lawyer with Stamford's Domestic Violence Crisis Center. She says abuse victims are often the first to report someone dangerous. "A lot of times, victims of domestic violence will express that extra level of fear and safety concern because they know their abuser has a weapon."

Only police can use the Red Flag Law, but abuse victims have another option. If they get a temporary restraining order, a judge can also take weapons away.