The next big issue in the US debate over guns - whether people have a right to be armed in public - is moving closer to Supreme Court review.
A provocative ruling by a panel of federal appeals court judges in Chicago struck down the only statewide ban on carrying concealed weapons, in Illinois.
The ruling is somewhat at odds with those of other federal courts that have largely upheld state and local gun laws, including restrictions on concealed weapons, since the Supreme Court's landmark ruling declaring that people have a right to have a gun for self-defence.
In, 2008, the court voted 5-4 in District of Columbia v. Heller to strike down Washington's ban on handgun ownership and focused mainly on the right to defend one's own home. The court left for another day how broadly the Second Amendment of the US Constitution may protect gun rights in other settings.
Legal scholars say the competing appellate rulings mean that day is drawing near for a new high court case on gun rights.
The appeals court ruling in Chicago came early in a week that ended with the mass shooting in Connecticut that left 28 people dead, including 20 children at an elementary school and the presumed gunman.
Laurie Levenson, a professor at the Loyola Law School in Los Angeles, said that along with thorny legal issues, "we have the overlay of these tragedies hitting us on a somewhat regular basis."
The author of a book that traces the battle over gun control in the US said he thinks Supreme Court intervention is likely in the short-term.
"Since the Heller case, the next great question for the Supreme Court to decide was whether there is a right to carry guns in public," said UCLA law professor Adam Winkler, whose book "Gunfight" was published last year.
Roughly 40 states make it easy for people to carry a gun in public. But in California, New York and a few other states, local and state regulations make it difficult if not impossible to get a licence to carry a weapon.
Illinois and the District of Columbia have been the only places to refuse to allow people to be armed in public.
"In some of our most populated states, the right does not exist either because it's completely forbidden or practically forbidden," said Alan Gura, the lawyer who won the Heller case at the Supreme Court.
Gun rights advocates and gun control supporters are as split over the issue of having guns in public as they were over whether the US Constitution protected gun ownership at all - and along the same lines.
Jonathan Lowy, an attorney with the Brady Center to Prevent Gun Violence, said, "If law enforcement makes a determination that somebody would increase the danger to the public by carrying a loaded gun on the streets, then that person should not be carrying a loaded gun. Some people in the gun lobby want to tie the hands of law enforcement."
But Wayne LaPierre, chief executive officer of the National Rifle Association, said, "Clearly, the individual right under the Constitution does not apply only to your home. People have lives outside their home and the constitutional right applies outside their home."
Sometimes, LaPierre said, "The only thing to stop a bad guy with a gun is a good guy with a gun."
Judge Richard Posner of the 7th US Circuit Court of Appeals employed similar reasoning in his majority opinion striking down the Illinois law.
Posner said that threatening confrontations do not only or even principally occur at home. "A Chicagoan is a good deal more likely to be attacked on a sidewalk in a rough neighbourhood than in his apartment on the 35th floor of the Park Tower," the judge said.
He homed in on the distinction between inside the home and on the street in his questioning of another recent appeals court ruling that upheld New York's restrictive law on granting people permits to carry concealed weapons.
A unanimous panel of the 2nd US Circuit Court of Appeals said the requirement that people demonstrate a special need to carry a concealed weapon does not violate the Constitution.
"Our principal reservation about the Second Circuit's analysis is its suggestion that the Second Amendment should have much greater scope inside the home than outside simply because other provisions of the Constitution have been held to make that distinction," including the right to privacy that underlies the high court ruling striking down sodomy laws.
"Well of course, the interest in having sex inside one's home is much greater than the interest in having sex on the sidewalk in front of one's home. But the interest in self-protection is as great outside as inside the home," Posner said.
In dissent, Judge Ann Williams said governments have a strong interest in regulating guns on the street.
"It is common sense, as the majority recognises, that a gun is dangerous to more people when carried outside the home. When firearms are carried outside the home, the safety of a broader range of citizens is at issue. The risk of being injured or killed now extends to strangers, law enforcement personnel, and other private citizens who happen to be in the area," Williams said.
Gura represents the challengers to the New York law and he said he will ask the high court to review the 2nd Circuit ruling. Illinois Attorney General Lisa Madigan has not yet said whether the state will ask the full 7th Circuit court to reconsider its ruling or appeal to the Supreme Court.
So far, the Supreme Court has turned down appeals asking it to say more about guns. But that reluctance might fade if the court were presented with a split between appeals courts, typically a strong factor in attracting the justices' interest.
The Second Amendment talks about "the right to keep and bear arms and it's as if some courts want to take a giant eraser to the words 'and bear' and pretend that they're not there," said David Thompson, managing partner of the Cooper and Kirk law firm in Washington. Thompson represented some plaintiffs in the Illinois case.
Northwestern University law professor Eugene Kontrovich said the difference between the New York and Chicago courts over what it means to bear arms could be enough to persuade the Supreme Court to intervene.
Winkler, the UCLA professor, said he thinks the Illinois statute would fall if it were to put to a test at the Supreme Court, probably by the same 5-4 vote as in Heller. But it is hard to predict how the Supreme Court might rule on restrictions that fall short of an outright ban on the right to carry a loaded weapon in public for self-defence, he said.
"Public possession is a different issue than having a gun in your home," he said.