The National Basketball Association filed a lawsuit Tuesday against the players' union seeking a declaratory judgment that the lockout of players does not violate antitrust laws.

The NBA said the lawsuit, which was filed in Manhattan federal court, arises from the players' union's threatened use of antitrust litigation to extract a more favorable contract in ongoing negotiations.

The case is National Basketball Association v. National Basketball Players Association, et al, U.S. District Court, Southern District of New York, No. 11-5369.