In the United States v. Gilman case of 1953, the Supreme Court ruled on a dispute involving railroad stock ownership and antitrust laws. The U.S government sued under the Sherman Act to prevent three insurance companies from acquiring additional shares in two railroads, arguing that this would reduce competition among eastern railroads. The defendants argued that they were exempted from these restrictions by Section 5(11) of the Interstate Commerce Act (ICA), which allowed for such acquisitions with approval from the Interstate Commerce Commission (ICC). However, it was found that ICC's approval did not shield them from antitrust laws unless explicitly stated by Congress. Therefore, their acquisition could still violate antitrust law if it substantially lessened competition or created monopoly power. The court held that while ICA exemptions may exist regarding certain transactions approved by ICC, those exemptions do not automatically extend to all provisions of other acts unless specifically provided for in legislation.

In the dissenting opinion for United States v. Gilman, Justice Douglas argued that the majority's decision to uphold a conviction based on evidence obtained through wiretapping violated the Fourth Amendment rights of citizens against unreasonable searches and seizures. He contended that wiretapping was an invasive form of surveillance equivalent to entering someone's home without their consent or knowledge, thus constituting an illegal search. Furthermore, he believed this ruling set a dangerous precedent by allowing law enforcement agencies to use such intrusive methods without any checks or balances in place. This could potentially lead to widespread abuse of power and erosion of civil liberties if left unchecked. Therefore, he disagreed with the court’s ruling upholding Mr.Gilman’s conviction as it was based on evidence collected via unconstitutional means.