Syndication exclusivity (also known as syndex) is a federal law ( 47 U.S.C. § 76.103) implemented by the Federal Communications Commission (FCC) in the United States that is designed to protect a local television station's rights to syndicated television programs by granting exclusive broadcast rights to the station for that program in their local market, usually[citation needed][example needed] defined by a station's Nielsen Designated Market Area.
As a result, any airings of the same program on cable networks and, more commonly, superstations must be blocked by the local cable provider upon request from the local station. Broadcast television stations have the option of signing programming deals with or without syndex protection, but they stand to have audiences significantly diluted in markets without protection. Syndex protection is rarely enforced in regards to conventional cable networks, which (particularly since the late 1990s) often concurrently maintain rights to a particular program during the period of a broadcast syndication deal.