In the United States v. Bryan case of 1949, the Supreme Court ruled on whether a defendant's refusal to answer questions before a grand jury could be considered contempt of court if they were not informed that their answers could potentially incriminate them. The defendant, Mrs. Ethel B. Bryan, was subpoenaed by a federal grand jury investigating alleged violations of federal laws and refused to answer certain questions based on her belief that she might incriminate herself in violation of the Fifth Amendment rights against self-incrimination. The Supreme Court held that while defendants have protection from self-incrimination under the Fifth Amendment, this does not excuse them from appearing and testifying altogether in cases where it is unclear whether or not their testimony will indeed be self-incriminating. Furthermore, it was determined that ignorance about potential for self-incrimination did not exempt one from being charged with contempt for refusing to testify before a grand jury. This ruling clarified an important aspect regarding testimonial obligations under law: individuals cannot refuse outright to testify but can invoke their right against self-incincrimination question-by-question as each arises during proceedings.

In the dissenting opinion of United States v. Bryan, Justice Jackson disagreed with the majority's decision to uphold a conviction for failure to register under the Federal Security Act. He argued that this was an unfair application of criminal law because it punished someone who may not have known they were required to register in the first place. The defendant, he pointed out, had no way of knowing she was violating any laws by failing to register as her organization wasn't clearly defined as "subversive" at that time. Furthermore, he criticized how vague and broad definitions within such acts could potentially lead to arbitrary enforcement and abuse of power by authorities. He also expressed concern over how these types of convictions could infringe upon First Amendment rights due their potential chilling effect on free speech and association.