In the case of Murel et al. v. Baltimore City Criminal Court et al., 1971, petitioners Murel and another defendant were convicted in a Maryland state court for possession and control of gambling devices. They appealed their conviction on the grounds that evidence used against them was obtained through an unconstitutional search warrant, violating their Fourth Amendment rights. The Supreme Court of United States denied certiorari (refused to review the lower court's judgment), stating that there was no substantial federal question involved in this case because it did not present any novel or unsettled questions regarding constitutional law or interpretation thereof. The defendants argued that the affidavit supporting the issuance of a search warrant lacked probable cause as it relied heavily on information from an anonymous informant whose reliability had not been established by police before obtaining said warrant. However, both lower courts upheld their convictions ruling that sufficient corroborating details were provided by surveillance which confirmed parts of informant’s tip thus establishing his credibility indirectly. This decision reaffirmed existing legal principles surrounding Fourth Amendment protections against unreasonable searches and seizures while also emphasizing importance of corroboration when dealing with anonymous informants.

In the dissenting opinion for Murel et al. v. Baltimore City Criminal Court et al., Justice William O. Douglas argued that the petitioners' constitutional rights were violated due to their inability to cross-examine a key witness in their trial, who was deceased at the time of appeal but had given testimony during an earlier hearing which was used against them in court. He believed this contravened both the Confrontation Clause and Due Process Clause of the Constitution, as it denied defendants their right to challenge evidence presented against them through cross-examination - a fundamental aspect of fair trials under American law. Furthermore, he criticized his fellow justices for failing to grant certiorari (review) on these grounds, arguing that they were neglecting their duty to uphold constitutional protections by allowing such violations go unchecked.