In a decision with far-reaching implications for the future of the Internet and the role of the Federal Communications Commission, the U.S. Court of Appeals for the District of Columbia ruled Tuesday that the agency lacks the authority to regulate the policies of Internet service providers.

In Comcast Corp. v. FCC, the court considered whether the FCC could bar Comcast from interfering with its customers’ use of peer-to-peer networking applications. The FCC acknowledged it had no explicit regulatory authority to do so, but the agency claimed it had “ancillary” jurisdiction over such network management practices.