Timothy Courtois' family had been worried about him for weeks. They repeatedly told police in Biddeford, Maine, that the 49-year-old was off his meds for bipolar disorder. And police were also told he had guns. But still, because he wasn't doing anything that rose to the legal definition of imminent threat, police said their hands were tied.

"We're very limited — very, very limited to what we can do," says Biddeford Police Deputy Chief JoAnne Fisk. "Just because somebody has a hunch, we will investigate it. But everybody has rights, and you have the right to bear arms in this country."

It was both frustrating and a relief to police and the family when Courtois was finally arrested for speeding down the highway to what could have been a tragedy. Police found an AK-47, handguns and several boxes of ammunition in Courtois' car as he drove toward New Hampshire, he reportedly told police, to shoot a former employer.

Federal law bars gun sales to the mentally ill only if they've ever been deemed by a judge to be mentally incompetent or involuntarily committed. That may have been the case with Courtois, but states' reporting of such things to the federal database is spotty, and very often, it doesn't show up when a gun seller does a background check.

"It's just shameful to allow people who the law has already said to be too dangerous to have guns to still be able to easily access those guns at licensed dealers," says Dennis Henigan, president of the Brady Campaign to Prevent Gun Violence.

Henigan says Maine has reported just a couple of dozen people out of what may be thousands who should be disqualified — and Pennsylvania, for example, has reported just one.

"Our estimate is that we're probably still missing a million of these records, and this is ridiculous," Henigan says.

But even if reporting were perfect, experts question how much gun violence would be prevented. Federal law doesn't require background checks when guns are sold privately, and even at licensed dealers, the law may not be disqualifying the most dangerous of the mentally ill.

"Do we really know that we're finding the right people?" says Jeff Swanson, a psychiatric professor at Duke University School of Medicine. He says it might make sense legally to only disqualify those who have been officially deemed by a court to be mentally unfit. That's the due process courts require. But clinically, Swanson says, it's a pretty arbitrary line.

"A system that relies on searching for official records may never find those individuals. There are lots of people who have an involuntary commitment history who have virtually zero risk of violence," Swanson says.

Take, for example, someone who is involuntarily committed because he's clinically depressed and not eating. Swanson says more relevant risk factors would be a history of violence or substance abuse. But such an in-depth review of every case would be impractical and, experts concede, still not reliable.

"Our ability to predict human behavior is not that great. We don't even think that we can be right most of the time," says Joel Dvoskin, a forensic and clinical psychologist at the University of Arizona Medical School. "I don't pretend I'm Carnac the Magnificent and that I can hold my hand up to somebody's forehead and tell them what they're going to do in three years. It's a dicey business."

With the risk so uncertain, Dvoskin says, it becomes harder to justify revoking someone's rights in the name of public safety. Richard Bonnie, a law and psychiatry professor at the University of Virginia, agrees. At the very least, he says, there should be better systems set up for people who lose their gun rights to apply to get them back. But also, Bonnie says, there needs to be room for more discretion and ways to take less draconian measures — for example, to temporarily suspend gun rights or seize weapons that someone already has.

"There are cases that arise of someone who does seem to be losing it, but it does not appear that they meet commitment criteria. Under those circumstances, precautionary interventions are needed to try to interrupt access to weapons," Bonnie says.

Some states do allow such intermediate interventions, and some also go beyond the federal law revoking gun rights, for example, of anyone who's ever been in treatment for mental illness. But given the small percent of mentally ill who commit gun violence, Bonnie cautions casting such a wide net could actually hurt more than it helps.

"The payoff in terms of preventing violence would be very little. Indeed, you probably would pay a very heavy price by discouraging people from treatment, which in the long run probably would result in more violence, not less," Bonnie says.

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