People under 21 are no longer able to buy semiautomatic assault rifles in Washington as of Jan 1. It is the first of several new state measures intended to reduce gun violence. The National Rifle Association has already filed suit.

Previously, state law barred the assault weapons’ sale to those under 18. The new rules, approved by voters in a ballot initiative in November, come alongside dozens of moves by other states to strengthen gun control regulations in the absence of federal action.

“It is a meaningful step in the right direction,” said Christian Heyne, legislative director at the Coalition to Stop Gun Violence, on Washington’s initiative. “Gun violence on the whole is such a complex problem. We need to have complex solutions, comprehensive solutions. This is a part of that conversation.”

In addition to the age restrictions, Washington’s new rules state that gun dealers must wait 10 days before delivering semiautomatic assault rifles they sell. That is designed, in part, to prevent impulsive action. The rules also require anyone buying a semiautomatic assault rifle to have completed a gun safety training in the last five years. The measure also imposes criminal penalties for unsafe gun storage, and requires more extensive background checks for purchases of the assault weapons.