Contamination by Extraneous Influences. The Supreme Court held that “any [unapproved] private communication, contact, or tampering ... with a juror during a [criminal] trial ... [is] presumptively prejudicial.” However, the Supreme Court also held that a post-trial hearing “in which the defendant has the opportunity to prove actual bias” is sufficient to decide the prejudice issue. Thus, the Constitution “does not require a new trial every time a juror has been placed in a potentially compromising situation.” Instead, trial courts should investigate jurors exposed to extraneous influences to determine whether prejudicial impact has actually occurred. Extraneous influences include juror contact with other people and extrinsic materials.

The trial court may conduct a hearing to identify and evaluate whether an extraneous influence has resulted in juror bias, though not all outside contacts necessitate a hearing. The scope of any such hearing, however, is limited by 606(b) of the Federal Rules of Evidence, which, “[d]uring an inquiry into the validity of a verdict,” bars juror testimony about emotional reactions or mental impressions developed during deliberations, but provides exceptions for the introduction of extraneous information or outside influence, and racial bias. A defendant who can establish prejudice as a result of extraneous influences is entitled to a new trial.