NBA sues players union

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

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

"The union's improper threats of antitrust litigation are having a direct, immediate and harmful effect upon the ability of the parties to negotiate a new collective bargaining agreement," the lawsuit said.