In Ziang Sung Wan v. United States (1924), the U.S. Supreme Court ruled that a confession obtained through physical or psychological coercion is inadmissible as evidence in court because it violates the Fifth Amendment's protection against self-incrimination. The case involved Ziang Sung Wan, who was accused of murder and had confessed to the crime after being subjected to brutal treatment by police officers while he was detained in China before his extradition to America for trial. He appealed his conviction on grounds that his confession had been coerced and should not have been admitted into evidence at trial. The Supreme Court agreed with him, stating that confessions must be voluntary to be admissible as evidence, thereby setting an important precedent regarding interrogation practices and defendants' rights.

In the dissenting opinion for Ziang Sung Wan v. United States, Justice McReynolds expressed his concern over the majority's decision to admit a confession obtained through coercion as evidence in court. He argued that this was against American principles of justice and fairness, which prohibit any form of torture or duress to extract confessions from suspects. According to him, such practices were reminiscent of medieval times when physical torment was used to obtain 'truth'. The justice further stated that it is not enough for courts merely to disapprove or condemn these methods; they must refuse admittance into trials any confessions extracted under such circumstances. This would serve as a deterrent against law enforcement resorting to brutal tactics in their quest for truth and uphold the integrity of judicial proceedings.