In the United States v. Schwimmer case of 1928, the Supreme Court ruled against Rosika Schwimmer, a Hungarian immigrant who applied for U.S. citizenship but declared that she would not take up arms to defend the country due to her pacifist beliefs. The court held that this refusal was grounds for denying her application as it violated Section 4 of the Naturalization Act which required applicants to be willing and able "to support and defend" the Constitution and laws of America against all enemies. In a 6-3 decision, Justice Pierce Butler wrote in his majority opinion that while freedom of thought is protected under American law, an individual's personal convictions cannot interfere with their duty towards national defense if they wish to become citizens.

In the dissenting opinion for United States v. Schwimmer, Justice Oliver Wendell Holmes Jr. argued that the court's decision to deny Rosika Schwimmer citizenship due to her pacifist beliefs was a violation of her freedom of thought and speech. He contended that while she may have held views contrary to popular sentiment, this did not make her any less loyal or devoted to the principles upon which America was founded - namely liberty and justice for all. Furthermore, he pointed out that many great figures in history had also been pacifists who refused military service on moral grounds yet were still considered patriots in their own right. Therefore, he concluded it was unjustifiable and unconstitutional to reject someone’s application for citizenship solely based on their personal convictions against war.