The United States v. The South-Eastern Underwriters Association was a landmark case that established the federal government’s ability to regulate the insurance industry. The case was argued on May 15, 1944, at the Supreme Court of the United States. In this case, the Justice Department pursued an antitrust suit against the South-Eastern Underwriters Association, an industry-wide organization of inter-state insurance companies, for violations of the Sherman Antitrust Act of 1890. The South-Eastern Underwriters Association was accused of using its collective economic power to set insurance prices below cost, thereby being in violation of the Sherman Act.

At the heart of the Supreme Court’s decision in United States v. The South-Eastern Underwriters Association was the question of whether Congress had the power to regulate the activities of insurance companies. The majority of the Court, in an opinion written by Chief Justice Stone, held that the Sherman Antitrust Act did not apply to the insurance business. In its opinion, the Court called the insurance industry's activities "a matter of internal concern of each state" and, since no state could regulate the activities of insurance companies in another, Congress had no power to regulate the activities of the insurance companies as a whole.

The Court’s decision in United States v. The South-Eastern Underwriters Association was a significant victory for the insurance industry and gave state legislatures the authority to regulate insurance policies. The ruling also set the precedent that the federal government could not take action against an insurance company for violating the Sherman Antitrust Act.

Despite the impact of the ruling, however, the United States v. The South-Eastern Underwriters Association was met with criticism from both the public and Congress. Critics argued that the decision weakened the Sherman Antitrust Act by giving insurers a “safe harbor” from federal regulation. As such, Congress passed the McCarran-Ferguson Act in 1945, which granted exemption from federal regulation to insurers engaging in certain activities.

Although the ruling in United States v. The South-Eastern Underwriters Association was a setback for the federal government’s ability to enforce antitrust legislation, the Court’s decision has given way to new federal regulations. For example, in 2021, Congress passed the Competitive Health Insurance Reform Act of 2020. This new law gives federal authorities the power to take action against insurers that engage in anticompetitive behavior. The new law has been hailed as an important step towards ensuring fair and competitive insurance markets.

Overall, United States v. The South-Eastern Underwriters Association was a significant case in American legal history. The decision of the Court determined the federal government’s ability to regulate the insurance industry and affirmed the power of state legislatures to regulate the activity of insurance companies. Despite its initial impact, the ruling has served as a stepping stone to new laws and regulations that aim to protect consumers from anticompetitive business practices in the insurance industry.