07/24/2012 11:41 am ET Updated Sep 23, 2012

Lax Gun Laws Allow Terrorism at Home

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We are shocked and saddened by the massacre in Aurora, Colo. But Aurora is part of a pattern, not an isolated incident. Two days earlier, 17 were hurt outside a bar in Tuscaloosa, Ala., when a gunman opened fire.

There is no safe zone.

Rep. Gabrielle Giffords and 18 others were shot in a Tucson, Ariz., shopping center. Virginia Tech students were mowed down on campus. In Chicago, 228 people have already lost their lives to gun violence as of mid-June. Nationwide, there have been 60 mass shootings since the Tucson horror, according to the Brady Campaign. Every year, about 100,000 Americans are victims of gun violence, with about 30,000 killed. Aurora is shocking -- but the shock has become routine.

We fixate on the details of the alleged killer. James Holmes was an honor student who ran into trouble, dropped out of school and, it seems to me, suffered from depression. He saw himself as the Joker, the villain without a cause, eager only to sow violence and disruption for its own sake. Dressed in black body armor, he walked into the movie theater playing the new Batman movie carrying two handguns, a shotgun and an assault rifle. There was no defense when he opened fire.

Our leaders offer condolences and prayers, as President Obama and Republican presidential candidate Mitt Romney did immediately. But we need both prayer and policy to provide for domestic tranquility. Depression isn't isolated. Mass depression and mass access to guns is a recipe for massacre. We must do more than mourn. We must act to limit domestic terrorism.

Holmes purchased the four guns he carried in local Colorado gun shops along with 6,000 rounds of ammunition in the last 60 days. How could he arm himself with an assault rifle that is useful only to hunt humans? It was easy because in Colorado, it was perfectly legal. According to the Brady Campaign, this is the current state of gun laws in Colorado:

There is no ban on assault weapons, no ban on high-capacity ammunition magazines, no registration requirements, no gun owner licensing requirements, no background checks for Internet sales, no "good cause" required for a concealed carry permit, no limit on the number of handguns you can buy in one purchase.

Our police chiefs campaign hard for a ban on assault weapons that put them at risk. A weak federal assault weapons ban existed from 1994 until George Bush let it lapse in 2004. During that time, the number of crimes committed with assault weapons declined dramatically. But the National Rifle Association -- the powerful gun lobby -- campaigned hard against the ban and intimidated politicians in both parties.

Now the gun lobby has won. People have begun arming themselves, as if that would protect them. Last year, nearly half (47 percent) of Americans said they have a gun in their home. In 1959, 60 percent of Americans supported a law to ban possession of handguns except by police and other authorized persons. By 2011, only 26 percent supported it. Last year for the first time, a majority of Americans said they were opposed to a law to make it illegal to manufacture, sell or possess assault weapons.

In "The Second Coming," the poet William Butler Yeats captured our time when he warned "the ceremony of innocence is drowned; the best lack all conviction, while the worst are full of passionate intensity."

How many must die before "the best" stand and speak? We must revive the ban on assault weapons in America. The Joker's goal of creating chaos through violence is not a joke. Arming ourselves is not a solution; it is a defeat. We must demand action to defend the domestic tranquility against a gun industry, lobby and culture that now pose a clear and present danger.