In Shepard v. United States (1933), the U.S Supreme Court ruled that a defendant's constitutional rights were violated when the trial judge allowed jurors to consider evidence not presented in court. The case involved Mr. Shepard, who was accused of poisoning his wife and subsequently convicted for murder based on circumstantial evidence. During deliberations, one juror shared with others an article about another similar crime committed by Shepard which had no connection to the current case at hand; this information was not introduced as evidence during trial proceedings nor cross-examined by defense attorneys. The Supreme Court held that such extraneous prejudicial information could have influenced jury members' decision-making process and thus compromised their impartiality, violating due process under the Fourteenth Amendment of Constitution. This ruling emphasized that all facts considered by a jury must be formally presented in court where they can be challenged or rebutted through established legal procedures ensuring fairness and justice.

In the dissenting opinion for Shepard v. United States, Justice McReynolds disagreed with the majority's decision to uphold Shepard's conviction. He argued that the trial court had improperly allowed hearsay evidence - specifically, statements made by Shepard's deceased wife prior to her death - into testimony. According to McReynolds, these statements were not relevant as they did not directly pertain to any cause of death and could have unduly influenced the jury against Shepard due their emotional nature. Furthermore, he contended that this ruling violated a fundamental principle of law: an accused has a right to confront his accusers in court; since Mrs. Shepard was dead at time of trial she couldn't be cross-examined about her accusations against Mr.Shepard which is unfair according him.