To be American is to live among guns. They are central to our history, our nightly news, our national mythology. Americans’ intimacy with firearms was written into our founding document.

The availability of guns provides a sense of security to those who wield them and of vulnerability to those who don’t. Nowhere is this tension more stark than within America’s homes, where so much of its lethal violence begins.

In nine of the 10 deadliest mass shootings in modern American history, the gunmen had records of threatening, stalking or physically abusing loved ones. An analysis by the advocacy group Everytown for Gun Safety found that 54 percent of mass shootings were connected to family violence. Indeed, most mass shootings — which are often defined as shootings of four or more people — are episodes of domestic violence.

It is here, in the spaces between husbands and wives, beaus and lovers, parents and children, that the government has shouldered its greatest burden of keeping dangerous weapons out of dangerous hands. It’s a responsibility that for too long has been neglected, as even existing laws go unenforced or have loopholes that make them ineffective.

On July 18, 2016, police officers in Sinking Spring, Pa., responded to a 911 call from Megan Short. When they arrived at her home, she told the officers she was afraid of her husband. They told her to get an order of protection. She said she would.

The next day, her husband, Mark Short, went to a nearby licensed gun dealer and bought a .38-caliber, five-shot revolver.

Mr. Short easily passed the federal background check to buy his gun — he had no prior convictions, and his wife hadn’t sought a restraining order, which could have barred him from buying or possessing a firearm. There was nothing the police could do. Yet something was terribly, and obviously, wrong with him. Weeks before the 911 call, security officers had been called to break up a loud argument in a Philadelphia hotel room; when they arrived, they found the Shorts. Then, on Aug. 1, Mr. Short was demoted at work for excessive absences.

If Ms. Short lived in Oregon, Washington or California, the police or even her mother, worried about the safety of her family, could have asked a judge for what’s known as an extreme-risk protection order. Connecticut and Indiana have similar laws. Extreme-risk orders allow law enforcement agencies and immediate family members to petition the court to temporarily prohibit a person’s access to firearms by showing he is a danger to himself or others. But no one could do that for Ms. Short, and rather than seek an order herself, she decided to escape.

On Aug. 6, movers were on their way, and Ms. Short’s mother and other relatives were waiting at her new apartment to help unpack. But Mr. Short picked up his new handgun and shot and killed his wife and their three children — 8-year-old Lianna, 5-year-old Mark Jr. and 2-year-old Willow, all still in their pajamas. He even killed the family dog. Then he killed himself.

Law enforcement groups are now pushing for extreme-risk laws in 20 additional states. Congress could unify the patchwork of protections by passing national legislation.

In Connecticut, a recent study found that over a 14-year period extreme-risk protection orders prevented one suicide for every 10 to 20 guns seized. These orders could also abate not only family violence but even mass shootings more broadly. For example, Aaron Alexis, the gunman who killed 12 people at the Washington Navy Yard in 2013, had previous run-ins with the police and had sought treatment for his mental illness, yet nothing prohibited him from arming himself.

Extreme-risk protection orders are part of a common-sense slate of reforms Congress could pass to reduce violence in the home, including measures to broaden prohibitions to include boyfriends, girlfriends and other family members, and to deny gun rights to stalkers; to prohibit gun possession by anybody issued a temporary restraining order; to fix the national instant background check database and improve notification when a partner fails a background check; and, ultimately, to take guns away from people known to be dangerous to those closest to them.

For the state to allow abusers to own guns is for the state to sanction killing in the home. Protecting families — saving American lives — is the government’s highest calling. Or at least it should be.