In Remmer v. United States, the Supreme Court examined whether a juror's impartiality was compromised due to external influence and if this constituted grounds for a new trial. The defendant, Fred W. Remmer, had been convicted of tax evasion in federal court when it came to light that an unknown person suggested to one of the jurors that he could profit from giving a verdict favorable to Remmer. This incident was reported by the juror himself and investigated by FBI agents without knowledge or participation of either defense counsel or prosecutor until after trial concluded. On appeal, the Supreme Court held that any private communication with a juror during a trial about matters pending before them is considered presumptively prejudicial and requires investigation as such interference casts doubt on fairness of proceedings even if no harm is shown directly affecting jury’s decision-making process.

In the dissenting opinion for Remmer v. United States, Justice Felix Frankfurter disagreed with the majority's decision to remand the case back to district court for a hearing on whether or not an external influence had prejudiced a jury member against the defendant. He argued that there was no need for further inquiry because it was clear from existing evidence that no harm had been done. The juror in question had reported an improper communication immediately and both he and his fellow jurors were instructed by the judge not to let it affect their deliberations. Furthermore, Frankfurter believed that any investigation into what effect this incident might have had on other jurors would be speculative at best and could potentially undermine public confidence in jury trials if allowed as precedent.