The 1st Circuit ruled that Facebook creator Mark Zuckerberg must defend himself in a copyright infringement lawsuit brought by former Harvard classmates who accused him of stealing computer code for the "spectacularly successful" social-networking Web site.

    The decision reinstates a 2004 lawsuit filed by ConnectU Inc. founders Cameron and Tyler Winklevoss and Divya Narendra, finding that the amended complaint contains a "viable hook on which federal jurisdiction can be hung."

    The Winklevoss brothers and Narendra claimed they hatched the idea for Facebook as undergraduates in 2003, but lacked the programming expertise needed to make it work, so they recruited Zuckerberg to help them develop their "embryonic website."

    The founders accused Zuckerberg of swiping their idea, business plan and unfinished source code and using them to secretly launch a competing social-networking site that ultimately became Facebook - now the nation's fifth most-visited Web site with more than 60 million users.

    By the time the plaintiffs had launched their own site, connectU.com, Zuckerberg's venture "had gotten an unbeatable head start in user traffic," the ruling states.

    "Harvard's traditional school color is crimson, but the founders saw red," Judge Selya wrote. The founders filed state-law misappropriation claims against Zuckerberg, his associates and Facebook, but later registered a copyright for their source code and amended the complaint to add a federal copyright claim.

    The district court granted defendants' motion to dismiss on grounds that it lacked subject-matter jurisdiction because the parties to the original complaint were not wholly diverse.

    The appellate court rejected the claim that a second lawsuit filed by ConnectU in federal court rendered the appeal moot. It then concluded that the amended complaint, which had dropped any allusion to diversity jurisdiction, replaced the original complaint "lock, stock and barrel," meaning the lower court had federal jurisdiction over the case.