U.S. President Barack Obama’s expansion of background checks for would-be gun buyers is being challenged in a lawsuit by a political activist who claims the changes violate the Constitution and the federal rule-making process.

Stymied by congress in prior attempts to enact gun-control legislation following mass shootings, the president on Jan. 5 announced a new interpretation of already-existing rules defining who is a firearms dealer. The new definition would subject more transactions -- including sales at gun shows and on the Internet -- to background checks, preventing sales to people deemed to be a danger to themselves or others.

Those measures and others were unveiled by Obama in a sometimes tearful televised speech that drew immediate criticism from gun-rights supporters.

“It is clearly arbitrary and capricious for the defendants, each and every one of them, to now suddenly adopt and implement a new and different interpretation for no other reason than the political preferences of temporary occupants of elected office,” attorney Larry Klayman said in a complaint filed at the U.S. court in West Palm Beach, Florida.

Klayman, the founder of the political watchdog group Freedom Watch, claims the background-check initiative violates the constitution’s Second Amendment, which the U.S. Supreme Court has said guarantees an individual’s right to bear arms for self-defense.

Rule Making

Even if constitutional, the redefinition circumvented the federal rule-making process, he said. Klayman, who said he’s a Florida resident and the owner of two 9-millimeter handguns and one .45 caliber weapon, is seeking a court order blocking the executive action and declaring the measures unlawful.

Named as defendants are the president, U.S. Attorney General Loretta Lynch and Thomas Brandon, who heads the federal Bureau of Alcohol, Tobacco, Firearms and Explosives. 

Patrick Rodenbush, a spokesman for the U.S. Justice Department, didn’t immediately reply to a telephone message seeking comment.

The case is Klayman v. Obama, 16-cv-80087, U.S. District Court, Southern District of Florida (West Palm Beach).