## Facts

- A private cargo claimant filed an admiralty libel in rem in federal district court against the Peruvian steamship *Ucayali* over an alleged breach of a charter party to carry sugar to New York.
- The *Ucayali* was seized upon filing of the libel.
- The Republic of Peru intervened, asserted sole ownership, and filed a claim stating it was not a general appearance and did not waive defenses, including sovereign immunity.
- Peru secured the vessel’s release by posting a $60,000 surety bond containing the same non-waiver reservation and conditioned on payment of any final award.
- Peru took limited testimony and sought procedural relief while repeatedly stating it acted only with full reservation and without waiver of sovereign immunity.
- Peru requested recognition of immunity from the U.S. Department of State; the State Department recognized immunity and the Attorney General filed that certification in the district court.
- The district court refused to dismiss and release the vessel/bond, ruling Peru had waived immunity through its litigation conduct.
- Peru sought original extraordinary relief in the Supreme Court (prohibition/mandamus) to stop further district-court jurisdiction and to require recognition of immunity.

## Issues

1. Whether the Supreme Court may issue mandamus or prohibition to restrain a district court’s continued exercise of jurisdiction in an admiralty in rem suit despite the availability of ordinary appellate review.
2. Whether a district court must accept the Executive Branch’s certification that a friendly foreign sovereign’s vessel is immune and therefore release the res (or substitute bond).
3. Whether Peru waived sovereign immunity by filing a claim, posting bond, seeking extensions, and taking testimony while expressly reserving immunity.

## Decision

- The Supreme Court granted leave to file the petition and ordered issuance of extraordinary relief to terminate the district court’s exercise of jurisdiction.
- The Court held it had statutory power to issue mandamus/prohibition, exercised only for matters of public importance or where especially appropriate; a recognized immunity claim by a friendly foreign sovereign met that standard.
- The Court held that, once the State Department recognized and allowed Peru’s immunity claim and the Attorney General presented that certification, the district court was required to release the vessel (and bond) and leave the private claimant to diplomatic channels.
- The Court held Peru did not waive immunity by simultaneously presenting the claim to the State Department and the court or by taking defensive procedural steps with explicit non-waiver reservations.

## Legal Principles

- The Supreme Court may use mandamus or prohibition to restrain a district court’s further proceedings when the question is of public importance or the remedy is particularly appropriate.
- In a private admiralty in rem suit, when the Executive Branch certifies that a friendly foreign sovereign’s immunity for its vessel has been recognized and allowed, the court must surrender the res and dismiss the proceeding as to that property.
- Courts do not examine the basis for the Executive’s immunity determination once formally recognized and presented.
- A foreign sovereign does not waive immunity by protective litigation steps taken after seizure—such as filing a claim, posting bond, seeking time, or preserving testimony—when it expressly preserves and asserts immunity.

## Conclusion

The Court required immediate termination of an admiralty in rem action against a foreign sovereign’s vessel after the State Department recognized immunity, holding that the district court had to release the res and that Peru’s reserved, defensive participation did not waive sovereign immunity.


Ex parte Republic of Peru, 318 U.S. 578 (1943)