One of the law blogs I enjoy reading, The Appeal, has a new “Explainer” series, where lawyers “help unpack” (AKA “explain”) some of the most complicated issues in the criminal justice system. I never thought harmless error was particularly complicated. Appellate courts sometimes find that trial courts erred, but they don’t care. It’s sort of a “yeah, whatever” doctrine. Here is a refreshing take on harmless error from someone far, far less jaded than I am.

For those who only have time for one harmless factoid: for much of American history, ANY error required reversal. The doctrine allowing a constitutional error to be “harmless” did not arrive until 1967. That year, in Chapman v. California, the Supreme Court created a couple of new rules: (1) constitutional errors can be “harmless,” and (2) constitutional errors require reversal unless the government proves the error was “harmless beyond a reasonable doubt.”

Should we scrap the doctrine? Follow the incentives and it’s not too hard to predict what would happen if we did. Appellate judges, who already treat criminal convictions like family heirlooms, would unquestionably respond by narrowing the underlying constitutional rights. Scholars have documented this exact dynamic in related contexts. It happened with qualified immunity, habeas review, and other areas where strong remedies clash with judicial reluctance. Courts preserve desired outcomes by whatever path is available. Confiscate their guns and they’ll shrug their shoulders and come at you with a rusty stilleto.