Professional Real Estate Investors, Inc. (PRE) (defendant), maintained a resort hotel in California that allowed guests to rent movies on videodiscs that could be played privately in the guest’s hotel rooms. Columbia Pictures Industries, Inc., and seven other motion-picture studios (the studios) (plaintiffs) brought a lawsuit against PRE, alleging that PRE’s rental practices infringed upon the studios’ copyrights in the movies that were contained on the videodiscs. PRE counterclaimed, alleging that the studios’ actions violated antitrust law as concerted action and that the studios were not entitled to immunity under the Noerr doctrine, because the lawsuit was a pretense to restrain competition. The district court granted summary judgment in favor of PRE on the copyright claim, but on remand, the court granted summary judgment in favor of the studios on the antitrust counterclaim. PRE appealed the decision, but the court of appeals affirmed. PRE appealed again, and the United States Supreme Court granted certiorari.