The harmless constitutional error doctrine is as baffling as it is ubiquitous. Although appellate courts rely on it to deny relief for claimed constitutional violations every day, virtually every aspect of the doctrine is subject to fundamental disagreement and confusion. Judges and commentators sharply disagree about which (and even whether) constitutional errors can be harmless, how to conduct harmless error analysis when it applies, and, most fundamentally, what harmless constitutional error even is — what source of law generates it and enables the Supreme Court to require its use by state courts. This Article offers a new theory of harmless constitutional error, one that promises to solve many of the doctrine’s longstanding mysteries. There is widespread consensus that harmless constitutional error is a remedial doctrine, in which the relevant question is the appropriate remedy for an acknowledged violation of rights. But harmless error is in fact better understood as an inquiry into the substance of constitutional rights: a purported error can be harmless only if the defendant’s conviction was not actually obtained in violation of the defendant’s rights. That approach can help solve the doctrine’s longstanding riddles. It explains why harmless error is binding on state courts; it clears up confusion about the relationship between the doctrine and statutory harmless error requirements; it shows which errors can never be treated as harmless without effectively being eliminated; and it provides useful guidance for how courts should conduct harmless error analysis where it applies. Most importantly, it reflects a more realistic understanding of the right-remedy relationship that makes it harder for courts to surreptitiously undermine constitutional values.
* Associate Professor of Law, Washington University in St. Louis. For useful conversations and comments, I thank Jon Abel, Scott Baker, Danielle D’Onfro, Garrett Epps, Peter Joy, Ron Krotoszynski, Ron Levin, Leah Litman, Greg Magarian, Sandy Mayson, Justin Murray, Matt Owen, Wilson Parker, Neil Richards, Ian Samuel, Liz Sepper, and Peter Wiedenbeck, work-shop participants at Washington University School of Law and the 2017 Southeast Junior-Senior Workshop, as well as the editors of the Harvard Law Review. I owe particular debts of thanks to Brandon Garrett, who did his best to show me the error of my ways, and to Richard Re, whose own insights into these questions helped crystalize my thinking. I am also grateful to Alison Siegler, Erica Zunkel, and their students at the Federal Criminal Justice Clinic at the University of Chicago Law School, who helped me first think through these issues several years ago when we collaborated as co-counsel on an amicus brief involving some difficult harmless error issues. See Brief for 57 Criminal Law and Procedure Professors as Amici Curiae in Support of Respondent, United States v. Davila, 133 S. Ct. 2139 (2013) (No. 12-167).