The District’s first responders gather Monday morning near the Navy Yard. (Matt McClain / The Washington Post)

As soon as the body count was confirmed at the Navy Yard shooting on Monday, popular attention shifted to the usual questions about the suspect’s mental health and criminal past, and how an individual with such warning signs could slip through the cracks and cause such carnage.

The NRA predictably attempted to outflank any criticism by posting a pointed headline from ABC News on its Web site: “D.C. Gun Laws Some of the Strictest in the U.S.”, which noted that beyond a 10-day waiting period on gun purchases, both carrying a gun openly and concealing it is illegal in D.C.

Still, none of this stopped Aaron Alexis from allegedly entering a gun shop in Lorton, Va., and buying a gun that he brought onto the military grounds and used in the murder of 12 people.

The state of Virginia, which on its state police Web site boasts “one of the most complete records repositories in the nation” for conducting criminal background checks, requires no waiting period for gun purchases.

As of this writing, it seems that Alexis, despite being arrested repeatedly for violent and gun-related offenses, did everything short of being convicted of a felony —  one sure thing that would have pinged the state-of-the-art Virginia background check system.

This laissez-faire approach certainly isn’t unique to Virginia — it’s part of our nation’s crazy quilt of disparate gun laws, and the gun-rights lobby is clear about wanting to keep it that way.

States that require waiting periods for gun sales are vastly in the minority — only 10 states and D.C. have waiting periods for some or all firearms. A similar patchwork approach exists in gun-permitting.

Take the examples of Virginia, Arkansas and California — three states with very different gun cultures. Virginia requires a gun store background check for sales, but if you’d like permission to conceal and carry that new gun, you only have to complete an online course. You can complete the course whether or not you are a resident of Virginia, and if you happen to live in one of 25 other states that has a nonresident deal with Virginia, your brand-new concealed carry permit will be honored in your home state, no questions asked. What better to pair with Virginia’s computerized point-of-sale criminal background checks than an online course to determine who gets a concealed carry permit? No live-fire training necessary.

By contrast in Arkansas, according to Lieutenant Cora Gentry, of the concealed carry department of the Arkansas State Police, applicants do need to go through a six-hour live gun instruction class, which includes a shooting range test, before being issued a concealed carry permit.

What about California, which like Washington, D.C., boasts some of the toughest gun laws in the country? You can’t even buy a gun in California without passing a written test, and concealed carry permits are granted on a case-by-case basis, with some jurisdictions, in mostly urban areas, nearly always denying them and those in in rural areas nearly always granting them.

California also prides itself on a one-of-a-kind program, the Armed Prohibitive Persons System, which keeps records of who is prohibited from owning a gun, matching it with who actually owns a gun. The underfunded system theoretically makes it so that a person who owns a legal gun, but then gets convicted for a felony or even certain misdemeanors, can be retroactively stripped of his or her firearm. Unfortunately, according to a recent report in the Los Angeles Daily News, California has a backlog of 20,000 people who might be prohibited from owning firearms and whose names have yet to be checked. Still, Attorney General Kamala Harris noted that her department has seized more than 10,000 firearms under the law.

The Second Amendment reads: “A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.”

Does this mean that every American citizen, save the seriously mentally ill and felons, deserves to own a gun? That is fundamentally what most of our state and federal laws assume; it is what allowed Aaron Alexis to apparently legally obtain a gun and use it in the commission of a crime that killed 12 people.

It’s time we renegotiated the terms of our national conversation from a reactive standpoint on guns — everyone has the right to own a gun unless they’ve shown otherwise — to a proactive stance: Prove that you should own a gun.

Maria De La O is a journalist and documentary filmmaker in San Francisco.