18 U.S.C. §1519 provides: “Whoever knowingly alters, destroys, mutilates, conceals, covers up, falsifies, or makes a false entry in any record, document, or tangible object with the intent to impede, obstruct, or influence the investigation or proper administration of any matter within the jurisdiction of any department or agency of the United States or any case filed under title 11, or in relation to or contemplation of any such matter or case, shall be fined under this title, imprisoned not more than 20 years, or both.” The Miss Katie, a commercial fishing boat, was inspected by Officer John Jones of the Florida Fish and Wildlife Conservation Commission. Miss Katie was far enough from the Florida coast to be in exclusively federal waters, she was nevertheless within Officer Jones’s jurisdiction. Because he had been deputized as a federal agent by the National Marine Fisheries Service, Officer Jones had authority to enforce federal, as well as state, fishing laws. Officer Jones noticed three red groupers that appeared to be undersized hanging from a hook on the deck. Violation of those regulations is a civil offense punishable by a fine or fishing license suspension. Officer Jones ultimately determined that 72 fish fell short of the 20-inch mark. With few exceptions, the measured fish were between 19 and 20 inches; three were less than 19 inches; none were less than 18.75 inches. Officer Jones directed D to leave the fish segregated in crates until the Miss Katie returned to port. Before departing, Officer Jones issued Yates a citation for possession of undersized fish. At port, Officer Jones surmised that the fish brought to port were not the same as those he had detected during his initial inspection. One of the crew members admitted that, at D’s direction, he had thrown overboard the fish Officer Jones had measured at sea, and that he and Yates had replaced the tossed grouper with fish from the rest of the catch. After 32 months, criminal charges were lodged against D. By the time of the indictment, the minimum legal length for Gulf red grouper had been lowered from 20 inches to 18 inches. No measured fish in D’s catch fell below that limit. P argued that §1519 sets forth “a documents offense” and that its reference to “tangible objects” subsumes “computer hard drives, logbooks, [and] things of that nature,” not fish. D was convicted. On appealed. The Eleventh Circuit found that because “tangible object” was “undefined” in the statute, the Court of Appeals gave the term its “ordinary or natural meaning,” i.e., its dictionary definition, “having or possessing physical form.” It affirmed. The Supreme Court granted certiorari.