In the United States v. Inadi case of 1985, the Supreme Court ruled that a co-conspirator's out-of-court statements are admissible as evidence even if the defendant has not had an opportunity to cross-examine them prior to trial. The court held that such statements do not violate the Confrontation Clause of the Sixth Amendment, which guarantees defendants in criminal cases a right "to be confronted with witnesses against him." This decision overturned previous rulings requiring confrontation before admitting hearsay evidence from non-testifying co-conspirators. The court reasoned that these types of declarations were often more reliable than other kinds of hearsay and their exclusion could hinder effective prosecution of complex conspiracy crimes.

In the dissenting opinion for United States v. Inadi, Justice Brennan, joined by Justices Marshall and Blackmun, argued that the majority's decision to allow out-of-court co-conspirator statements without requiring a showing of unavailability was inconsistent with previous Supreme Court precedent and undermined defendants' Sixth Amendment right to confront witnesses against them. The dissenters contended that such hearsay evidence should only be admissible if there is no other way to obtain the testimony (i.e., if the witness is unavailable) and its reliability can be assured. They believed that this ruling could lead to abuse as prosecutors might rely on such statements instead of producing live witnesses who could be cross-examined in court. Furthermore, they pointed out potential issues regarding whether or not these types of declarations were truly reliable enough for admission into evidence without further scrutiny.