## Facts

- Sharpnack was indicted in the U.S. District Court for the Western District of Texas for four sex-offense counts involving two boys at Randolph Air Force Base, a federal enclave in Texas.
- The indictment relied on the Assimilative Crimes Act (ACA), 18 U.S.C. § 13, to apply Texas criminal statutes (Vernon’s Texas Penal Code arts. 535b, 535c) enacted in 1950.
- The charged conduct allegedly occurred in 1955, after both the 1948 ACA revision and the 1950 Texas enactments.
- The ACA provides that acts on a federal enclave not punishable by federal enactment are punishable under the “then effective” law of the surrounding state.
- The district court dismissed the indictment, holding Congress could not constitutionally assimilate state criminal laws enacted after the ACA (treating such “prospective” incorporation as impermissible delegation).
- The United States appealed directly to the Supreme Court under 18 U.S.C. § 3731.

## Issues

1. Whether 18 U.S.C. § 13 is constitutional to the extent it applies, on federal enclaves, state criminal laws enacted after the federal statute’s enactment.
2. Whether prospective incorporation of evolving state criminal law into federal enclave prosecutions is an impermissible delegation of Congress’s power to define federal crimes.

## Decision

- The Supreme Court reversed the dismissal and remanded.
- The Court held the ACA is constitutional insofar as it makes applicable to a federal enclave a subsequently enacted criminal law of the state in which the enclave is located.
- The Court reasoned that Congress made a federal legislative choice to use state law as a reference to fill gaps where Congress has not made conduct punishable.
- The Court treated the ACA as a permissible “reference” statute that borrows state law as a standard, rather than conferring federal lawmaking power on states.
- The Court relied on Congress’s broad authority to legislate for federal enclaves under Article I, § 8, cl. 17.
- A dissent argued the statute improperly allows future state legislation to define federal crimes, violating separation-of-powers requirements for federal criminal lawmaking.

## Legal Principles

- Congress may, for federal enclaves, incorporate by reference the “then effective” criminal law of the surrounding state to punish conduct not made punishable by federal enactment.
- Prospective incorporation of later-enacted state criminal laws via a federal reference statute is not, by itself, an unconstitutional delegation when Congress has set the governing federal rule (state law fills gaps where federal law is silent).
- The ACA operates only where Congress has not otherwise criminalized the conduct; it functions as a gap-filler to maintain a complete criminal code on enclaves.

## Conclusion

The Court upheld the Assimilative Crimes Act’s prospective incorporation feature, allowing federal enclave prosecutions to proceed under state criminal laws enacted after the ACA when no federal statute punishes the conduct, and reversed the dismissal of Sharpnack’s indictment.


United States v. Sharpnack, 355 U.S. 286 (1958)