As lawmakers on Capitol Hill revive talk of gun control following the school shooting in Newtown, Conn., a federal appeals court in Washington this week will take a look at the propriety of new firearm regulations that target the sale of semi-­automatic rifles.

Federal firearm authorities in July 2011 issued so-called “demand letters” to every gun dealer in Arizona, California, New Mexico and Texas, requiring thousands of retail sellers to report sales of more than one semi-automatic rifle to the same person at one time or during a period of five consecutive business days.

The federal Bureau of Alcohol, Tobacco, Firearms and Explosives, a component of the U.S. Justice Department, said the request for information arose in the effort to investigate and combat firearm trafficking along the southwest border with Mexico. A judge last year upheld the legality of the letters, which the ATF said would allow agents to trace firearms discovered at crime scenes more quickly.

The challengers in the case, which is set for a January 9 hearing in the U.S. Court of Appeals for the D.C. Circuit, contend the reporting requirement would amount to the creation of a national firearms registry, which Congress has expressly prohibited.

The Brady Center to Prevent Gun Violence, represented by Arnold & Porter, filed a brief in support of the government in the appeals court. The plaintiffs in two consolidated suits are the nonprofit trade association National Shooting Sports Foundation and two gun retailers in Arizona. D.C. Circuit judges Judith Rogers and Karen LeCraft Henderson, with Senior Judge Harry Edwards, will hear the dispute.

“The overarching issue is the question of whether ATF has the authority to do what they’ve done here,” said Richard Gardiner, a solo practitioner in Fairfax, Va., who represents the gun retailers in the case, J&G Sales Ltd. and Foothills Firearms LLC. “Historically, the ATF has pushed the edge of the envelope to see how far they can go.”

Federal firearm licensees create records of all firearm transactions, but that information — including the buyer’s name, age and residence — isn’t automatically transmitted to the ATF. Judge Rosemary Collyer of U.S. District Court for the District of Columbia said in her ruling last year that the scope of the ATF demand letters “is sufficiently narrow to pass muster.” The letters, Collyer said, require the reporting of information that firearms sellers are already required to maintain.

Gun dealers have long been required to report multiple sales of pistols or revolvers, and the ATF has the authority to inspect dealer records, without a warrant, during a criminal investigation, Collyer noted. “Congress has effected a delicate balance between ATF’s regulation of firearms and the right to privacy held by lawful firearm owners,” she wrote. “ATF’s demand letter did not disturb that balance.”

RELYING ON THE REPORTS

Multiple sales reports, DOJ lawyers said in court papers filed in the D.C. Circuit, enable ATF investigators to quickly identify the purchaser of a suspected “crime gun” and also to detect unlawful activity. DOJ’s Michael Raab of the Civil Division, who will argue for the ATF, said the demand letters request information from only about 7 percent of the total number of federal firearms licensees in the country.

The ATF’s “efforts to investigate and combat arms trafficking across and along the southwest border were hindered by the lack of data on multiple sales of the semi-automatic rifles increasingly used by Mexican drug cartels,” DOJ lawyers said in a brief in the D.C. Circuit.

Last May, the ATF said it opened 120 criminal investigations based on more than 3,000 multiple sales reports from dealers between August 2011 and early 2012 in the four border states. Dealers in those states are required to disclose information about multiple purchases of certain high-caliber semi-automatic rifles with the ability to accept a detachable magazine.

The challengers of the demand letters, according to the Brady Center, “take the position that life-saving law enforcement leads must sit gathering dust in gun dealer files, ready to be accessed only to solve a violent crime after it has shattered families, terrorized communities and led to the destabilization of our southern neighbor.”

Arnold & Porter partner Steven Reade, representing the center, said in a friend-of-the-court brief that the challengers’ position “is wrong as a matter of law and dangerous as a matter of policy.”

The ATF demand letters, said Gardiner, who represents the firearms dealers, “are generating paper for the purpose of generating paper.” The government, he said, “is catching people who go to gun stores and fill out paperwork.”

Mike Scarcella can be contacted at mscarcella@alm.com.