For that minority of people with untreated mental illness that may drive them to violence, identifying them and getting them into treatment can be formidable tasks psychiatrists note.
"You can't be involuntarily treated unless you're an imminent danger to yourself or others," says Lehman. "Just because someone speaks loudly and scares other people doesn't mean they're an imminent threat to others. I think that's the dilemma here. [For Loughner] was scary, but he wasn't directly threatening anybody."
In Arizona, courts would have required that two clinicians evaluate Loughner and conclude that he was a danger to himself or others or both to initiate committing him involuntarily to a mental health facility, but that would have involved forcing him to be evaluated.
Some have questioned whether the Tucson massacre makes a case for more lenient requirements on involuntary commitment, but Robinowitz warns that "there's a tendency to overreact" following violent incidents.
"It becomes an issue of balancing public health and individual civil rights," she says. "The pendulum has gone from a time [in the 1940s and 1950s], when it was relatively easy to force people to have treatment against their will," to now, when there is much more emphasis on protecting the rights of individuals.
Psychiatrists agree that at least one positive thing that can come out of the tragedy in Tucson is a better awareness of the need for mental health services, especially within schools and colleges.
"It's an opportunity to put the message to the public at large that mental illness does not equal violence," Robinowitz says. "If we treat it as something secret and dark and awful, that makes it less likely that people are going to seek care. We also need to make sure that people have access to some degree of mental health services and that we fund these services, because so often they are the first to get cut for financial reasons."
A part of ensuring that those in need get help, psychiatrists say, is alerting the proper authorities to worrisome behavior in a peer or family member.
"If it's someone that they know, like a fellow student, talking to school authorities would be a good idea. If it's a friend or they know the family, let the parents know. If they are making direct threats, it can be reported to the police," Lehman says.
ABC News' Katie Moisse contributed on this report.