Section I of this Comment reviews the Supreme Court's jurisprudence on confessions, provides a close reading of Miller v. Finton, 474 U.S. 104 (1985), and reviews the division among the federal circuits over the standard of review for voluntariness determinations on direct appeal. Section II analyzes the literature on standards of review and focuses on two vexing problems in this field-the application of law to fact (hereinafter "mixed questions") and the constitutional fact doctrine. These two issues frame the analysis of voluntariness determinations. Section III analyzes these determinations and defends the application of de novo review in cases on direct appeal.