In the United States v. Maine et al., also known as the Massachusetts Boundary Case of 1980, the Supreme Court was tasked with determining boundaries for coastal states' submerged lands in relation to federal jurisdiction. The case involved a dispute between several New England states and the U.S. government over who had rights to certain offshore resources, including fisheries and potential oil deposits beneath continental shelf areas extending seaward from state coastlines into Atlantic Ocean waters. The court ruled that each coastal state's boundary extended three geographical miles directly outwards from its coastline, but not beyond this limit unless specifically granted by Congress or recognized by common law principles of international relations before 1953 when Submerged Lands Act (SLA) came into effect. This decision clarified how far individual states could exercise their sovereignty over marine resources off their coasts under SLA provisions granting them "lands beneath navigable waters" up to three nautical miles seaward from low-water mark along coastlines.

In the dissenting opinion for United States v. Maine et al., also known as the Massachusetts Boundary Case, Justice Harry Blackmun disagreed with the majority's decision to use a straight baseline method in determining coastal boundaries between states and federal waters. He argued that this approach was inconsistent with international law principles which typically favor a sinuous or irregular line following the coast's natural contours. Furthermore, he believed that using such an arbitrary boundary could potentially infrive on state rights by extending federal jurisdiction into areas traditionally controlled by individual states. Lastly, he expressed concern over potential negative impacts on offshore resource management and environmental protection efforts due to confusion or disputes arising from unclear territorial delineations.