In the case of Port of Portland et al. v. United States et al., 1971, the Supreme Court ruled on a dispute between private and public port authorities over rates for services provided to shipping lines. The Federal Maritime Commission (FMC) had previously determined that the Port of Portland's rates were just and reasonable, but this decision was challenged by several privately-owned Pacific Coast ports who argued that these lower rates constituted unfair competition as they were subsidized by tax revenues. The Supreme Court held in favor of the FMC’s ruling, stating that it did not exceed its authority in approving such rate schedules set by publicly owned ports like Portland's despite their ability to use tax revenue subsidies which private entities could not access. This landmark decision affirmed public port authorities' rights to set their own service charges within federal guidelines without being considered anti-competitive or discriminatory against private competitors.

In the dissenting opinion for the case of Port of Portland v. United States, it was argued that the majority's decision to uphold federal jurisdiction over certain aspects of port operations conflicted with traditional state authority over local commerce and infrastructure. The dissenters believed that this interpretation expanded federal power beyond its constitutional limits, infringing on states' rights. They contended that ports are inherently local entities whose operation should be governed by state law unless they directly impact interstate or foreign commerce in a way which necessitates federal intervention. Furthermore, they disagreed with the majority's view that Congress had intended to regulate all aspects of port activities through its passage of various maritime laws; instead, they interpreted these laws as only applying to specific areas where national uniformity is necessary. Therefore, according to their perspective, not every aspect falls under such regulation and some remain within states’ purview.