## Facts

- Kuapa Pond, a shallow Hawaiian fishpond on Oʻahu, was privately owned under long-standing Hawaii law and separated from Maunalua Bay by a barrier beach.
- The owners leased the pond and surrounding land to Kaiser Aetna to develop a marina-style residential community.
- Kaiser Aetna dredged and enlarged the pond, cut through the barrier beach, and created a channel connecting the pond to Maunalua Bay, making the marina navigable to and from the Pacific.
- Before construction, the Army Corps of Engineers advised that no permit was required under § 10 of the Rivers and Harbors Appropriation Act of 1899.
- After completion, the United States asserted the improved waterbody was “navigable waters of the United States” and that the federal navigational servitude required the marina to be open to the public without compensation.
- Petitioners operated the marina as a private facility, controlled access, and charged fees.

## Issues

1. Whether the improved marina, though navigable and connected to navigable waters, could be subjected to a federal public-access requirement under the navigational servitude without triggering the Fifth Amendment duty to pay just compensation.
2. Whether the federal government’s navigation-related authority permits eliminating a private owner’s right to exclude the public from the marina without compensation.

## Decision

- The Supreme Court reversed the Ninth Circuit.
- The Court held that the improved pond was within the meaning of “navigable waters of the United States” for purposes of federal regulatory authority.
- The Court held that compelling public access would take a core property interest—the right to exclude—and therefore required just compensation.
- The Court rejected the view that the federal navigational servitude creates a categorical exemption from the Takings Clause whenever Congress acts to promote navigation.
- If the United States sought public access, it had to proceed through eminent domain and pay just compensation.

## Legal Principles

- The right to exclude others is a fundamental attribute of property and cannot be taken by the government without just compensation.
- Federal authority over navigable waters (including the navigational servitude) supports substantial regulation, but does not automatically defeat Takings Clause protections.
- A government-mandated public right of access that results in physical occupation or invasion by the public can constitute a taking rather than mere regulation.
- Reasonable, investment-backed expectations—including reliance on governmental assurances and established state property law—bear on whether government action is a compensable taking.

## Conclusion

Even when privately improved waters fall within federal regulatory power as navigable waters, the government may not require that a private marina be opened to the public by extinguishing the owner’s right to exclude unless it pays just compensation under the Fifth Amendment.


Kaiser Aetna v. United States, 444 U.S. 164 (1979)