In the 1986 case Kentucky v. Stincer, the U.S. Supreme Court ruled that a defendant's Sixth Amendment right to be present at his trial is not violated when he is excluded from a hearing on competency of two child witnesses if his presence does not contribute to ensuring fairness of the proceeding. The court held that although defendants have a right to be present at all stages of their trials, this right can be outweighed by other interests or policies such as protecting minor victims from further trauma and intimidation in sexual abuse cases. In this particular case, it was determined that Stincer's absence did not hinder his opportunity for effective cross-examination nor did it affect his ability to fully communicate with counsel about matters relating to proceedings.

In the dissenting opinion for Kentucky v. Stincer, Justice Marshall argued that the defendant's Sixth Amendment right to be present at his own trial was violated when he was excluded from a competency hearing. He contended that this exclusion prevented him from fully participating in his defense and potentially influencing the outcome of the hearing. The majority held that since no factual issues were raised during this proceeding, there was no need for Stincer to be present; however, Marshall disagreed with this reasoning. In his view, even if only legal arguments were made during such hearings, defendants should still have a constitutional right to attend them because their presence could affect how these arguments are presented and received by judges or juries.