California will become the first state that allows family members to ask a judge to remove firearms from a relative who appears to pose a threat, under legislation Gov. Jerry Brown said Tuesday he had signed.
The bill was proposed by several Democrats and responds to a deadly rampage in May near the University of California, Santa Barbara.
Supporters had said such a measure could have prevented the attacks, winning out over critics who said it would erode gun rights.
Law enforcement authorities in Connecticut, Indiana and Texas can seek a judge's order allowing them to seize guns from people they deem to be a danger.
The new California law gives law enforcement the same option and extends it to family members.
It continues California's efforts to lead the nation in preventing firearm injury and death, said Amanda Wilcox, an advocate for the Brady Campaign to Prevent Gun Violence, whose daughter was a victim of gun violence.
The greatest effect might be in preventing suicides or intervening where there is a history of domestic violence, she said.