The Southern Pacific Company v. Jensen case in 1916 was a landmark decision by the U.S. Supreme Court that established what is known as the "Jensen line," which limits state jurisdiction over maritime affairs. The case involved an injured longshoreman, Martin Jensen, who sought compensation under New York's workers' compensation law from his employer, Southern Pacific Company. However, the court ruled in favor of Southern Pacific on grounds that federal maritime law superseded state laws concerning injuries at sea or on navigable waters within a state's boundaries (in this instance New York Harbor). This ruling effectively barred states from extending their worker protection laws to seamen and other maritime workers because it would interfere with uniformity in administering admiralty and maritime matters - thus establishing federal primacy over such issues.

The dissenting opinion in the Southern Pacific Company v. Jensen case, delivered by Justice Pitney, argued that the New York state law providing compensation for injured workers should apply to maritime employees as well. The majority ruling held that federal maritime law superseded state laws and therefore denied a widow's claim for her husband’s death while working on a ship docked in New York Harbor. However, Pitney contended this interpretation was too rigid and failed to recognize the evolving nature of commerce and industry. He believed it was within states' rights to extend their worker protection laws to cover those employed at sea when not engaged in navigation or interstate commerce activities. Furthermore, he pointed out that Congress had never legislated against such extensions by individual states; hence there was no conflict with federal jurisdiction over maritime matters.