When a gunman opened fire on the Virginia Tech campus, it was with a Glock 9 mm and a .22-caliber handgun he had legally purchased despite a history of mental instability.

Virginia law prohibits gun ownership by anyone who has been involuntarily committed to a mental institution. But Cho Seung-Hui skirted that law when a special justice ordered him in late 2005 to receive mental treatment on an outpatient basis.

Thus a troubled 23-year-old English major -- deemed by the justice to be "an imminent danger to himself as a result of mental illness" -- was free to buy the guns used to carry out the nation's most deadly mass shooting.

Some observers said the massacre might lead Virginia's generally gun-friendly legislature to take at least modest steps toward restricting gun access for those subjected to the mental commitment process.

Even gun rights supporters would agree that someone like Cho should not have had access to guns, said Harry Wilson, a Roanoke College political science professor and author of the book "Guns, Gun Control and Elections: The Politics and Policy of Firearms."

"You can't argue in favor of arming maniacs," Wilson said. "That would be the worst PR in the history of mankind."

State Sen. John Edwards, a Roanoke Democrat whose district includes Tech, agreed that the General Assembly needs to examine at what point mental illness should became a bar to gun ownership.

"It's a tough question," Edwards said. "Where to draw the line, I don't know."

When people buy a gun from a licensed dealer in Virginia, they must pass a state police background check for felony convictions, misdemeanors involving domestic violence and other prohibitors to gun ownership.

One question asks, "Have you ever been adjudicated legally incompetent, mentally incapacitated, or been involuntarily committed to a mental institution?" A "yes" to any one of those questions stops the sale.

Cho passed the test because he was not involuntarily committed, said Corinne Geller, a state police spokeswoman.

In December 2005, after Cho became depressed and potentially suicidal, a temporary detention order was issued against him. Tech police took him to a mental facility, where he remained overnight before appearing in Montgomery County General District Court.

At the hearing, special justice Paul Barnett found that Cho "presents an imminent danger to himself as a result of mental illness," according to court records. However, Barnett opted not send Cho back to the mental facility, instead ordering outpatient treatment.

Such an outcome fell short of an official adjudication of mental incompetence, Geller said, and there was no requirement that the information be forwarded to state police for inclusion in the database used to check gun purchasers.

Others were not so sure.

Del. Dave Nutter, R-Christiansburg, said he wonders whether Cho's brief stay at the mental facility should have barred him from purchasing his weapons, one in February and the second in March.

Nutter said he has asked the state attorney general's office for clarification. He also hopes that an upcoming study by the State Crime Commission will shed some light on the issue.

"This is a very complex question of state and federal law that we're going to have to work through," he said.

Complicating the matter even further is this: Once gun buyers pass the state background check to approve the purchase, they must fill out a second form for a federal screen before the firearm changes hands.

The federal form asks buyers if they have been adjudicated "mentally defective" or committed to a mental institution.

Bob Ricker, executive director of the American Hunters and Shooters Association, said he believes the federal guideline -- which does not refer to an involuntary commitment -- could possibly have blocked a sale to Cho.

A spokeswoman with the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives declined to comment Thursday.

Confusion over the issue, coupled with the possibility that Cho slipped through the cracks, should be enough to inspire proposed legislation at both the state and federal levels, Ricker said.

"I think clearly this is going to raise all kinds of issues in the future," Ricker said. "How do we prevent somebody like this from getting his hands on a gun?"

Although political observers did not predict such sweeping changes in Virginia, some states -- including New York and New Jersey -- require a police background investigation before residents are issued a handgun permit.

Ladd Everitt of the Coalition to Stop Gun Violence said such a law would likely have prevented Cho from killing two students in a Tech dorm early Monday morning and then 30 more people at an academic building before taking his own life.

"In this case you had a young man where there were so many warning signs," Everitt said, referring not just to Cho's mental commitment but also concerns about his disturbing writing for an English class and harassment of female students. "This is a situation where even a cursory contact with law enforcement, I think, would have stopped this."

But stopping a gun sale might not have stopped Cho, Wilson countered.

"From everything we've seen, this was a very determined individual," he said. "Instead of using the Columbine boys as his example, what if he turned to Timothy McVeigh and said, 'I'm going to blow up a whole building?' With the psyche you're dealing with, I don't think that's an unreasonable hypothesis."

Even if the debate in Virginia is limited to expanding the gun ban to cover some mentally troubled people who are not involuntarily committed, opponents argue that could discourage some people from seeking needed treatment.

If getting psychiatric help for a minor bout with depression meant losing your constitutional rights, "You'd say, 'The hell with it, I'm not going to get treatment,' " said Phillip Van Cleave, head of the Virginia Citizens Defense League.

If Cho really did pose an imminent danger, Van Cleave said, maybe the special justice should have issued an involuntary commitment order.

"This sounds like a judicial failure," Van Cleave said. "Why would you say somebody is a danger to themself and then just let them walk out the door?"