While Congress shamefully fails to face up to the toll of gun carnage, California’s lawmakers and voters are forging ahead with innovative safety measures, including mandatory background checks for the purchase of ammunition, not just guns.

The focus on ammunition sales, for which there are no federal controls, is a creative addition to Proposition 63, a ballot initiative that polls indicate should pass on Tuesday. It is being watched as a barometer of the re-emergence of gun controls as a national issue, exemplified by Hillary Clinton’s proposals for stronger laws after years of Democratic wariness at tackling the problem. In contrast, Donald Trump has the endorsement of the National Rifle Association and smugly echoes its destructive campaign to arm more and more citizens.

Three other states will offer voter initiatives on gun safety, as citizen movements try to circumvent the gun lobby’s intimidation of state legislators. In Maine and Nevada, voters will consider tighter background checks on gun sales. Voters in Washington State will decide whether judges should have the power to seize the weapons of people deemed threats to public safety and family members.

The California proposition — tailored to deal with the use of military-style assault weapons — includes a ban on high-capacity magazines holding more than 10 cartridges. The initiative would also stem the flow of firearms by requiring law enforcement to confiscate the weapons of newly convicted felons, and by applying penalties against owners who fail to report stolen or missing guns, which often disappear into the black market.