United States v. Maine

Background

The dispute is between the state of Massachusetts and the United States over whether Nantucket Sound—a shallow body of water south of Cape Cod between Martha’s Vineyard and Nantucket—counts as the state’s internal waters. After extensive hearings, a court-appointed Special Master found that Vineyard Sound was an inland bay but rejected Massachusetts’ claim for Nantucket Sound. Massachusetts argued it held “ancient title” through early English discovery and colonial occupation, tracing title from the Crown and old charters or the Treaty of Paris.

Reasoning

The central question was whether colonial exploitation and maps showed an occupation strong enough to create clear, original title before the freedom of the high seas became established. The Court reviewed the historical evidence and concluded it did not show exclusive acts by the Crown or the colony asserting authority over the entire Sound. Much activity cited—shellfishing, whaling near shore, salt making, and coastal maps—occurred in harbors or on land and did not prove control over the whole Sound. Massachusetts’ own 19th-century laws and charts treated the seaward boundary as three nautical miles and applied a stricter line‑of‑sight test, undercutting any long-standing claim. The Court therefore rejected the ancient-title claim and accepted the Special Master’s recommendation.

Real world impact

As a result, Nantucket Sound will not be treated as Massachusetts’ internal waters, and traditional international rights like innocent passage remain for parts claimed as territorial sea or high seas. The parties were ordered to enter a decree matching the Special Master’s findings, and broader questions about ancient title limits were reserved for another case.