If it's the former, then some gun control laws may be hard to sustain. If it's the latter, then the Second Amendment guarantees no more than a state's right to raise a militia, not an individual's right to own a gun.
The language of the amendment, with its extra commas, sounds stilted to modern ears, but has been used by both gun control advocates and opponents to support their positions:
"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."
So far, the Supreme Court hasn't been too helpful in interpreting what the amendment actually means.
The last time the high court visited the issue was in 1939's United States vs. Miller. Two men were charged with bringing a sawed-off shotgun from Oklahoma into Arkansas in violation of federal law. They claimed the law violated the Second Amendment's purported guarantee of an individual right to keep and bear arms.
Unfortunately, the Supreme Court majority in that case rejected the government's position -- that the Second Amendment guarantee was a collective state right, not an individual right -- without accepting the defendants' individual right position. Instead, the Supreme Court upheld the law on a government fall-back position: that the Second Amendment did not protect the right to bear the type of weapon the men were carrying.
So both sides of the debate have been using Miller over the decades to support their contrasting positions.
The debate in the scholarly community, as opposed to the courts, has been no contest. An article in the summer 1998 edition of the Harvard Journal of Law and Public Policy says the vast majority of constitutional scholars believe the Second Amendment was written to protect an individual right to bear arms.
Nevertheless, the courts and successive Congresses and administrations have ignored that near-consensus. Consequently, Attorney General John Ashcroft caused quite a stir when he wrote a letter to the National Rifle Association earlier this year asserting that he too believed in an individual's constitutional right to bear arms.
Up till now, no federal court of appeals has agreed. All that changed Tuesday with a ruling in the 5th U.S. Circuit Court of Appeals, which holds sway in Texas, Mississippi and Louisiana.
In the case that brought the ruling, the wife of Dr. Timothy Joe Emerson filed for divorce in Tom Green County, Texas, and, based on an alleged threat he made, asked a state judge for a protection order. It was granted.
Emerson was subsequently charged with possessing a Beretta pistol while under a protection order resulting from domestic violence, in violation of a 1994 federal law. However, a federal judge dismissed the case on constitutional grounds. The federal government appealed.
In the appeal, the Bush administration did not defend the law under the collective interpretation of the Second Amendment. Instead, government lawyers argued that the doctrine of "stare decisis" -- settled law and precedent -- precluded the appeals court from ruling against the law on constitutional grounds.
The appeals court panel examined the roots of the Second Amendment, including the letters of James Madison and other founding fathers, and concluded 2-1 "that the history we have recounted largely speaks for itself." Fear of a standing army led the country to adopt a Bill of Rights -- the first 10 amendments -- that included an individual right to bear arms.
"We reject the collective rights and sophisticated collective rights models for interpreting the Second Amendment," the court majority said. "We hold, consistent with Miller, that it protects the right of individuals, including those not then actually a member of any militia or engaged in active military service or training, to privately possess and bear their own firearms, such as the pistol involved here, that are suitable as personal, individual weapons and are not of the general kind or type excluded by Miller."
The appeals court recognized that its ruling was at odds with every other federal appeals court in the country.
Though it ruled for an individual right to bear arms, the court majority also held that the judge's order "is sufficient, albeit likely minimally so, to support the deprivation, while it remains in effect, of the defendant's Second Amendment rights." In other words, Emerson has an individual right to bear arms, but he forfeited that right temporarily.
The third judge on the appeals panel agreed with the ruling, but not with the two-judge majority's interpretation of the Second Amendment. The judge said it was not necessary to adopt a collective or individual interpretation in order to rule in the case.
The appeals court sent the case back down to the federal judge in Texas for a new ruling based on the appeals court decision.
There was no sign Wednesday that the Bush administration would try to take the issue to the Supreme Court, but in the end it may have little choice. Following Tuesday's ruling, an NRA official reportedly said the organization would look for similar cases to pursue throughout the 5th U.S. Circuit, where the appeals court ruling now holds sway.
The government, or an outside intervener in any of those cases could then try to push the issue into the Supreme Court. One of the criteria used by the Supreme Court when it decides to take a case is whether there is a conflict between the U.S. circuit courts of appeal.
Tuesday's ruling in the 5th U.S. Circuit created that conflict.
The Supreme Court itself may be split between the collective and individual interpretations of the Second Amendment.
Justice John Paul Stevens, leader of the four-member liberal block on the court, has volunteered from the bench that he believes there is no individual right to bear arms. Justice Clarence Thomas, one of the court's three consistent conservatives, said in a 1997 concurring opinion that he believes there is an individual right to bear arms.
A final resolution of the issue could come down to the court's two swing voters between the two philosophical blocks, Justices Sandra Day O'Connor and Anthony Kennedy.