Jared Lee Loughner, the man accused of shooting 20 people outside a Tucson grocery store on Saturday, probably will never get a chance to create the "new money system" he discusses in one of his rambling YouTube videos. But he can still have an important effect on public policy—if we let him.

After the shocking attack—which killed six people, including U.S. District Judge John Roll and 9-year-old Christina Green, and wounded 14, including Rep. Gabrielle Giffords (D-Ariz.)—there was no shortage of knee-jerk proposals for preventing future outbursts of senseless violence. Most of them would sacrifice Americans' freedom in a vain attempt to protect us from armed lunatics.

At a press conference on Saturday, Pima County Sheriff Clarence Dupnik decried Arizona's permissive gun laws. "I have never been a proponent of letting everybody in this state carry weapons under any circumstances that they want," he said, "and that's almost where we are." Paul Helmke, president of the Brady Campaign to Prevent Gun Violence, echoed Dupnik's concern, saying Arizona "has almost no gun laws."

The logic here may be even harder to follow than the reasoning that links the Tucson murders to Sarah Palin. A man bent on assassinating a member of Congress, a man who thinks nothing of gunning down a 9-year-old girl, is not likely to have compunctions about carrying a firearm without a permit.

In retrospect, it may seem obvious that someone like Loughner never should have been able to own a gun in the first place. "Why are crazy people allowed to buy weapons in this country?" wondered Time columnist Joe Klein. Helmke complained that "we make it too easy for dangerous and irresponsible people to get guns in this country." They noted that Loughner was suspended from college for disrupting classes with strange comments and that one of his fellow students called him "very disturbed."

But Loughner was never "adjudicated as a mental defective" or "committed to a mental institution," which would have disqualified him from buying a gun under federal law, and his behavior in school, though off-putting, was not violent. There is no reliable way of predicting which tiny percentage of the country's many oddballs and malcontents will convert weird ideas into homicidal actions. That reality may be scary, but it is not nearly as scary as a legal regime that strips citizens of their Second Amendment rights based on the opinions they express.

Even worse is a legal regime that imprisons eccentrics on the off chance that they will commit murder someday. Klein regretted that "we no longer lock up the mentally ill," while University of Maryland political scientist William Galston said civil commitment rules should be changed to "shift the balance in favor of protecting the community." Such a shift inevitably would mean locking up more people who pose no real threat to others.

If we can't pre-emptively detain all potential Loughners, maybe we can avoid saying things that might set them off. That censorious impulse, which imposes a madman's veto on speech that might unintentionally provoke "unbalanced people," is manifest not just in ritual calls for rhetorical restraint but in proposed legislation that would punish people for failing to heed those calls.

CNN reports that Rep. Robert Brady (D-Pa.) plans to "introduce legislation making it a federal crime for a person to use language or symbols that could be perceived as threatening or inciting violence against a Member of Congress or federal official." According to Brady, "the rhetoric is just ramped up so negatively, so high, that we have got to shut this down." Rep. James Clyburn (D-S.C.) wants to reinstate the "fairness doctrine," a policy of enforced balance on the airwaves that federal regulators abandoned because it had a chilling effect on speech.

The urge to do something in the wake of such a horrible crime is understandable but dangerous, as the grieving father of Christina Green suggested in a Today show interview. "In a free society," he said, "we're going to be subject to people like this. I prefer this to the alternative."

Jacob Sullum is a senior editor at Reason and a nationally syndicated columnist.

© Copyright 2011 by Creators Syndicate Inc.