## Facts

- Environmental and animal-protection groups challenged federal and state programs authorizing lethal control of mute swans.
- The Migratory Bird Treaty Act (MBTA) implements U.S. migratory bird treaties and generally prohibits killing protected migratory birds.
- A prior D.C. Circuit decision held mute swans were protected under the MBTA based on treaty coverage of a broader taxonomic group.
- Congress responded with the Migratory Bird Treaty Reform Act of 2004, amending the MBTA to apply “only to migratory bird species that are native to the United States or its territories.”
- The parties agreed mute swans are not native to the United States and were introduced for ornamental purposes.
- Plaintiffs sought to stop swan killings; the district court denied preliminary relief and entered final judgment for the government, concluding the amendment removed MBTA protection for non-native species.
- Plaintiffs appealed to the D.C. Circuit.

## Issues

1. Whether the MBTA, as amended in 2004 to cover only native species, still prohibits killing mute swans.
2. Whether a “sense of Congress” provision or treaty-related interpretive principles create ambiguity that preserves protection for mute swans despite the amendment.

## Decision

- The D.C. Circuit affirmed judgment for the government.
- The court held the amended MBTA does not protect mute swans because they are non-native, and the statute’s operative text limits coverage to native species.
- The court rejected reliance on a “sense of Congress” provision to alter or cloud the clear operative limitation in § 703(b)(1).
- The court held treaty-based arguments did not change the outcome because the statute was unambiguous and, in any event, a later-enacted statute controls over an earlier treaty to the extent of inconsistency.
- The court emphasized the migratory bird conventions are non-self-executing and do not independently supply domestic legal protection absent implementing legislation.

## Legal Principles

- When statutory text is unambiguous, courts apply it as written; policy statements such as “sense of Congress” provisions do not override clear operative language.
- Under the MBTA as amended by the Migratory Bird Treaty Reform Act of 2004, MBTA protections extend only to migratory bird species native to the United States or its territories.
- The canon disfavoring treaty abrogation does not apply where Congress has spoken clearly in a later statute.
- Under the last-in-time rule, a later federal statute prevails over an earlier treaty to the extent they conflict.
- Non-self-executing treaties do not create enforceable domestic law without implementing legislation; the implementing statute defines the enforceable scope.

## Conclusion

The D.C. Circuit held that Congress’s 2004 amendment limiting MBTA coverage to native species removes statutory protection for non-native mute swans, permitting government-authorized lethal control programs notwithstanding policy statements and treaty-based objections.


Fund for Animals, Inc. v. Kempthorne, 472 F.3d 872 (D.C. Cir. 2006)