MCI Telecommunications Corp. v. AT&T Co.
United States Supreme Court
512 U.S. 218 (1994)
Federal law required communications carriers to file tariffs with the FCC, but a separate provision let the FCC "modify" any of that requirement's terms. Beginning in 1979, the FCC used this modification authority to make tariff-filing optional ("permissive detariffing") for nondominant long-distance carriers like MCI Telecommunications Corp. (MCI) (defendant), aiming to reduce entry costs for newer competitors. Dominant carrier AT&T challenged MCI's failure to file tariffs before the FCC, which dismissed the complaint, prompting AT&T to seek D.C. Circuit review; that court held the FCC lacked authority for permissive detariffing, but the FCC issued a new order finding the policy was within its authority, and AT&T successfully sought summary reversal of that order from the D.C. Circuit.
Whether an agency's interpretation of a statute is entitled to deference when it uses a meaning that contradicts the meaning used in most dictionaries.