When a constitutional right conflicts with an evidentiary rule that would otherwise allow a piece of evidence to be admitted at trial, should the constitutional right be a "trump"? The Supreme Court and lower courts have often interpreted the Constitution to abstain from regulating questions of trial evidence. Taking the opposite course, courts have displaced evidence law to dramatic effect, as with the Court's exclusionary rule, Confrontation Clause, and punitive damages jurisprudence. In areas that provide a more attractive model, the Court has instead sought to accommodate constitutional and evidence law. The fundamental problem of adjudicating the intersection of the Constitution and the law of evidence has not been the subject of judicial standards or academic commentary. Despite their importance, such questions have been seen as confined to the particular criminal or civil procedure contexts in which they arise. Indeed, I argue that due to this neglect, important rights, such as the Miranda right, have been misunderstood as outliers, subconstitutional, or merely prophylactic. This Article develops why constitutional evidence law should in some respects be viewed apart from other areas of constitutional law. Second, I explore what norms should define the intersection of constitutional and evidence law. Third, I set out a framework in the form of standards of constitutional review, standards for avoidance, and canons of interpretation to govern intersections of constitutional law and the law of evidence. This Article ultimately seeks to describe the ways in which constitutional rights can intersect with rules of evidence and how courts might more clearly and consistently approach such conflicts and questions. Far from a subject to be avoided, constitutional rights have long protected against evidentiary abuses at trial. Conversely, evidence law principles can improve the effectiveness of constitutional protections and prevent unanticipated erosion of constitutional rights.
Brandon L. Garrett, Constitutional Law and the Law of Evidence, 101 Cornell Law Review 57-122 (2015)