The U.S. Supreme Court case Hill et al. v. Florida ex rel Watson, Attorney General in 1944 revolved around the issue of labor union regulation by states and its conflict with federal law. The state of Florida had passed a law requiring labor unions to register with the state and submit financial reports, among other requirements; non-compliance would result in criminal penalties. A local branch of the American Federation of Labor (AFL) refused to comply, arguing that this was an infringement on their rights under federal labor laws which superseded state regulations according to the Supremacy Clause in Article VI of the Constitution. However, when brought before court, it ruled against them stating that Congress had not explicitly stated its intention for national legislation to override any existing or future state laws regarding labor relations within their jurisdiction. This decision upheld states' rights over federal power concerning internal affairs unless otherwise specified by Congress but also highlighted potential conflicts between different levels of government over regulatory authority.

In the dissenting opinion for Hill et al. v. Florida Ex Rel. Watson, Attorney General, Justice Robert H. Jackson argued that the majority's decision was a departure from established principles of federalism and states' rights to regulate their own internal affairs - including labor relations - without interference from Congress or the Federal Government unless explicitly authorized by the Constitution itself. He contended that there was no constitutional basis for this intrusion into state sovereignty and warned against an overly expansive interpretation of Congressional power under the Commerce Clause which could undermine traditional limits on federal authority over states' domestic policies and institutions.