WASHINGTON — A gun-control case to be argued before the U.S. Supreme Court March 18 has exposed a division among state attorneys general over the meaning of the Second Amendment, the fiercely debated constitutional provision that guarantees Americans the right to "keep and bear arms."

Attorneys general from 31 states have filed a legal brief urging the high court to strike down the law being challenged in the case, the District of Columbia's strict, 32-year-old ban on handguns. Led by Texas Attorney General Greg Abbott, a Republican, the group backs a security guard who wants the district's statute to be ruled unconstitutional.

Lending their support to the District of Columbia are attorneys general from five other states — Hawai'i, Maryland, Massachusetts, New Jersey and New York — who say reasonable regulation of dangerous firearms is constitutional and keeps the public safe. A sixth attorney general, Democrat Lisa Madigan of Illinois, sided with the district in an earlier court filing, but declined to join the supporting states' latest brief.

The opposing views of the state attorneys general — who this week are attending their annual meeting in Washington, D.C. — are among more than 60 "friend of the court" briefs filed by elected officials, interest groups, academics and others in an effort to influence the Supreme Court. The politically charged case even has divided the Bush administration: Vice President Dick Cheney joined 305 members of Congress in urging the court to strike down the handgun ban, while Justice Department lawyers recommended remanding the case to a lower court for further review.

Filed as D.C. v. Heller, the case hinges on whether the security guard, Washington resident Dick Anthony Heller, may bring his work-issued handgun home with him to protect himself in what he considers a dangerous area of the nation's capital. Heller is challenging a district ordinance that forbids handguns at home and requires rifles and shotguns to be disassembled or trigger-locked.

The district says the ordinance improves public safety by keeping small, easy-to-conceal handguns off the streets, though that assertion has been fiercely challenged. Gun violence remains a problem in the district, where 181 people were murdered last year, and dozens of handguns have been seized by police in recent months. Supporters of the handgun ban stress that it has reduced violence and would be even more effective if the district's neighbors, Maryland and Virginia, had similar laws in place.

Attorneys for Heller contend the district's ban plainly violates the Second Amendment: "A well regulated militia, being necessary to the security of a free state, the right of the people to keep and bear arms shall not be infringed."

The case marks the justices' first evaluation of the Second Amendment since 1939, and raises a question that has been debated for decades: whether the amendment provides an individual right to possess guns, as Heller's lawyers argue, or a collective right associated with service in a "militia," such as a state-run National Guard unit.

If the court finds gun ownership to be an individual right, lawyers on both sides of the debate say, the case could leave state and local statutes across the country vulnerable to legal attack. That has prompted state attorneys general to enter the debate.

"We certainly believe the decision could affect Hawaii laws," Republican Hawaii Attorney General Mark J. Bennett told Stateline.org in a telephone interview. "We think that a decision that the Second Amendment prohibits strict gun-control laws is just wrong."

Hawai'i and the other states supporting the District of Columbia in the case have gun restrictions that are among the toughest in the nation, according to a state-by-state ranking released earlier this year by the Brady Campaign to Prevent Gun Violence, a Washington, D.C.-based group that advocates for tough gun-control laws.

While no states have outright handgun bans like the district's — only the city of Chicago does — the five states whose attorneys general are supporting the district do restrict the sale of assault weapons such as semi-automatic firearms, according to the Brady Campaign.

A Supreme Court ruling against the district's ban on a specific type of gun could jeopardize state statutes against assault weapons, said Dennis Henigan, the Brady Campaign's legal director. He said the five attorneys general supporting the district are doing so in the hopes of staving off potential future challenges against statutes in their states.

"The states that have a great deal at stake are coming into this case not because they are in favor of handgun bans, but because they are concerned about the ultimate implications (of the court's decision)," Henigan said.

The attorneys general supporting Heller in the case, meanwhile, are asking the high court for a narrow ruling that would strike down only the district's tough handgun ban but leave their own gun restrictions intact.

Though the attorneys general argue that the Second Amendment provides an individual right to guns, it would be "oversimplistic" to conclude they are against all forms of gun control, said James Tierney, the former attorney general of Maine and director of Columbia University's National State Attorneys General Program.

Indeed, in their brief, the attorneys general acknowledged the need for some government regulation of weapons, and statutes are on the books in all of their states that regulate guns in some way. Florida, for example, has a mandatory waiting period before weapons can be purchased and Pennsylvania requires guns to be sold with child-safety locks, according to the Brady Campaign.

"Reasonable minds can differ about the Second Amendment's scope — that is, about which government regulations are permissible," the 31 attorneys general wrote in their brief. "Subsequent cases may well present difficult questions about where precisely to draw that line. Those vexing issues are not presented in this case, however, and are appropriately left to another day."

Politics also factors heavily into D.C. v. Heller, according to Henigan.

He said some state attorneys general — who are elected in 43 states — likely sided with Heller as a way to show constituents they support an individual-rights reading of the Second Amendment, even as they seek to preserve their own state statutes regulating guns.

"These are political actors. They don't want to appear to be endorsing a handgun ban," Henigan said.