Nebraska and 37 other states are supporting a challenge to Chicago's ban on handguns.
The U.S. Supreme Court said earlier this fall that it would review a lower court ruling that upheld a handgun ban in Chicago. Gun rights supporters challenged gun laws in Chicago and some suburbs immediately following the high court's decision in June 2008 that struck down a handgun ban in the District of Columbia, a federal enclave.
The new case tests whether last year's ruling applies as well to local and state laws.
The 7th U.S. Circuit Court of Appeals upheld ordinances barring the ownership of handguns in most cases in Chicago and suburban Oak Park, Ill.
Judge Frank Easterbrook, an appointee of President Ronald Reagan, said that "the Constitution establishes a federal republic where local differences are to be cherished as elements of liberty rather than extirpated in order to produce a single, nationally applicable rule."
"Federalism is an older and more deeply rooted tradition than is a right to carry any particular kind of weapon," Easterbrook wrote.
But Nebraska Attorney General Jon Bruning says he and his fellow attorneys general want the high court to protect the constitutional right to bear arms and make it clear that cities and states have to follow the court's earlier rulings.
One of the plaintiffs in the Supreme Court case, Otis McDonald of Chicago, said he wants to own a firearm within city limits so he can protect himself in his home.
The goal of the Illinois lawsuit is to require state and local officials to follow the Supreme Court's 2008 ruling that eliminated Washington, D.C.'s handgun ban.