In the United States v. Calderon case of 1954, the Supreme Court examined whether a defendant's right to due process was violated when they were not allowed to cross-examine a government informant who had provided evidence against them. The defendant, Calderon, was convicted for narcotics distribution based on testimony from an undercover agent and an informant. However, the trial court did not allow Calderon's attorney to question the informant about his criminal record or his compensation from the government for providing information in this and other cases. On appeal, it was argued that this denial infringed upon Calderon’s Sixth Amendment rights which guarantee defendants in criminal prosecutions have compulsory process for obtaining witnesses in their favor. The Supreme Court ruled unanimously that denying cross-examination under these circumstances did violate due process rights guaranteed by Constitution as it prevented defense counsel from exposing potential biases or motivations behind witness testimonies thereby undermining its credibility before jury members. This landmark decision underscored importance of full disclosure during trials and reinforced constitutional protections afforded to all individuals facing prosecution.

In the dissenting opinion for United States v. Calderon, it was argued that the majority's decision to uphold a conviction based on evidence obtained through an illegal search and seizure violated the Fourth Amendment rights of the defendant. The dissenting justices believed that allowing such evidence to be used in court would set a dangerous precedent, effectively condoning unlawful police conduct and undermining citizens' constitutional protections against unreasonable searches and seizures. They contended that any evidence obtained in this manner should be deemed inadmissible regardless of its relevance or reliability, as permitting its use would incentivize law enforcement officers to disregard individuals' privacy rights with impunity. Furthermore, they expressed concern about potential abuses of power by authorities if such practices were allowed to continue unchecked.