In the case of Stewart v. United States, 1960, the Supreme Court ruled on whether a conviction could stand if it was based on evidence obtained through an unlawful search and seizure. The defendant, Robert Eliot Stewart, had been convicted for transporting stolen goods across state lines after police found these items in his home during a search that violated his Fourth Amendment rights. The court held that despite this violation, the conviction could still stand because there was sufficient other evidence to support it - specifically testimony from two accomplices who were also involved in the crime. This decision marked one of many instances where courts have grappled with how to handle illegally obtained evidence; while some argue such evidence should always be excluded as "fruit of the poisonous tree," others contend that excluding all such evidence would let too many guilty people go free.

In the dissenting opinion for Stewart v. United States, Justice Brennan disagreed with the majority's decision to uphold Stewart's conviction on grounds of perjury before a grand jury. He argued that the question posed to Stewart was fundamentally ambiguous and therefore could not form a basis for perjury charges. The ambiguity lay in whether "gambling" referred only to illegal gambling or also included legal forms of gambling such as horse racing and state lotteries. Given this uncertainty, Justice Brennan contended that it was unfair to hold Stewart accountable for interpreting the question in his own way - an interpretation which may have been entirely reasonable given his personal circumstances and understanding of what constitutes 'gambling'. Furthermore, he pointed out that there were no efforts made by prosecutors or jurors during trial proceedings to clarify this ambiguity; hence making it even more unjustifiable to penalize him based on their subjective interpretations post-trial.