In the 1989 case James v. Illinois, the U.S. Supreme Court ruled that evidence obtained illegally cannot be used in court to impeach a defendant's credibility during cross-examination unless it directly contradicts testimony given by the defendant on direct examination. The case involved Paul Lewis James who was convicted of murder and attempted murder based partly on physical evidence (a jacket) found during an illegal search of his home. During trial, he denied owning or wearing such a jacket but prosecutors introduced it as impeachment evidence to challenge his credibility. On appeal, the Illinois Supreme Court upheld this use of illegally seized evidence for impeachment purposes only - not as substantive proof of guilt - citing previous federal rulings allowing such usage under certain circumstances (the "impeachment exception"). However, upon further appeal to U.S., SCOTUS reversed this decision arguing that using unlawfully obtained evidence for any purpose violates Fourth Amendment protections against unreasonable searches and seizures; thus narrowing down scope of 'impeachment exception'. This ruling reinforced constitutional safeguards ensuring fair trials while also emphasizing importance of police adhering strictly to legal procedures when gathering evidences.

In the dissenting opinion for James v. Illinois, Justice Brennan, joined by Justices Marshall and Stevens, argued that the majority's decision to allow illegally obtained evidence to be used for impeachment purposes in court was a significant departure from previous Supreme Court rulings. They contended that this ruling undermined Fourth Amendment protections against unreasonable searches and seizures by providing an incentive for police officers to conduct illegal searches with the hope of obtaining incriminating evidence. The dissenters also pointed out that allowing such evidence could potentially lead to wrongful convictions due to its prejudicial effect on juries. Furthermore, they criticized the majority's reliance on Walder v United States (1954), arguing it was not applicable as it involved a defendant who had perjured himself about prior criminal behavior rather than one whose testimony merely contradicted illegally obtained evidence.