In the case of Ohio et al. v. United States et al., 1933, the Supreme Court was asked to determine whether a federal law that regulated milk prices conflicted with state laws on the same subject and thus violated principles of federalism. The State of Ohio had enacted legislation establishing minimum prices for milk in an effort to stabilize its dairy industry during the Great Depression. However, this clashed with a similar but more stringent Federal law aimed at regulating interstate commerce by stabilizing agricultural commodity prices nationwide. The court ruled unanimously in favor of upholding both sets of laws as constitutional, stating that they served different purposes and were not mutually exclusive or contradictory - one being designed to regulate intrastate commerce (Ohio's) while other sought to control interstate trade (Federal). It held that states have broad powers under their police power authority to protect public health and welfare which includes regulation of local aspects such as production, distribution & consumption within their jurisdiction even if it overlaps with Federal regulations governing broader economic issues like national market stability.

In the dissenting opinion for Ohio et al. v. United States et al., Justice McReynolds expressed his disagreement with the majority's decision to uphold a federal law that allowed states to regulate utilities within their borders, arguing it violated state sovereignty and exceeded Congress' power under the Commerce Clause of the Constitution. He contended that this ruling would lead to an overreach of federal authority into areas traditionally controlled by states, such as public utilities regulation. Furthermore, he argued that allowing such intrusion could potentially undermine state governments and disrupt local economies due to inconsistent regulations imposed by different levels of government on businesses operating across multiple jurisdictions. The justice also warned about potential abuses from unchecked expansion of federal powers at the expense of states’ rights.