In the case of Harlin v. Missouri (1978), the United States Supreme Court examined whether a defendant's constitutional rights were violated when he was not allowed to cross-examine a witness about his pending charges. The defendant, Harlin, had been convicted of robbery and murder in Missouri state court. During his trial, one of the main witnesses against him was an accomplice who had also been charged with these crimes but whose trial was still pending at that time. Harlin wanted to question this witness about his own charges to suggest that he might be testifying against Harlin in hopes of receiving leniency from prosecutors on his own case - thus undermining the credibility of this key prosecution witness. However, both lower courts did not allow such questioning due to concerns over prejudicing jury members against this other individual before they heard evidence related specifically to him during his separate upcoming trial. The U.S Supreme Court ruled 6-3 in favor of Missouri State upholding its decision by stating that while defendants generally have wide latitude under Sixth Amendment confrontation clause for cross-examining witnesses regarding their potential biases or motivations for testifying; there are limits if it risks unfairly prejudicing another person’s right towards fair proceedings.

In the dissenting opinion for Harlin v. Missouri, Justice Thurgood Marshall argued that the majority's decision to uphold a death sentence despite potential jury bias was fundamentally flawed. He contended that any juror who would automatically vote for the death penalty in every case involving intentional killing is not impartial and should be disqualified from serving on a capital sentencing jury. The fact that such jurors were allowed to serve in this case, he believed, violated the defendant's Sixth Amendment right to an impartial jury trial and his Fourteenth Amendment right to due process of law. Furthermore, Marshall criticized the majority for ignoring previous Supreme Court rulings which held that juries must consider all relevant mitigating evidence before deciding whether or not to impose a death sentence.