In the case of Union Bridge Company v. United States in 1906, the Supreme Court ruled that Congress has authority under the Commerce Clause to regulate bridges across navigable waters of the U.S., even if they are entirely within a single state. The Union Bridge Company had built a bridge over New York's Hudson River without federal approval and argued that it was not subject to federal regulation because it did not obstruct interstate commerce or navigation. However, the court disagreed and held that such structures could potentially interfere with interstate commerce by impeding navigation, thus falling within Congress' regulatory power. This decision expanded Congressional power under the Commerce Clause beyond direct regulation of trade between states to include potential obstructions or burdens on such trade.

In the dissenting opinion for Union Bridge Company v. United States, Justice Harlan argued that the majority's decision to allow Congress to regulate bridges across navigable waters encroached upon states' rights. He contended that while Congress has authority over interstate commerce and can prevent obstructions in navigable rivers, it does not have unlimited power to control structures within a state's boundaries unless they directly interfere with navigation or commerce. He believed this case was an example of federal overreach into areas traditionally controlled by states - specifically, their right to oversee infrastructure within their borders. Furthermore, he expressed concern about potential implications of such broad interpretation of congressional powers on other aspects of state sovereignty.