A motion filed Thursday by Manning's attorneys says Eric Inselberg's lawsuit is without merit.
The memorabilia dealer from Short Hills filed suit in January against Manning and other people, accusing them of doctoring jerseys, helmets and other equipment to make it look as though they'd been used during play.
Inselberg's attorney filed a motion this week to get the case returned to state court from federal court.
Inselberg was among a group of dealers accused of selling counterfeit jerseys. The Department of Justice dropped the case against him, but he said in court papers the Giants should be held accountable for ruining his business.