Suppose the Court rules 6-3 that a challenged law is valid. A lower court confronting materially similar facts must follow the controlling majority opinion, even if the three dissenters offer what the lower-court judge considers the better argument. The dissent can expose consequences of the new rule, preserve an alternative interpretation, and supply reasoning that advocates may ask a later Court to adopt. If doctrine changes, language first developed in dissent may become influential or even appear in a later majority opinion. That later development does not make the original dissent retroactively binding.

Dissents also perform an accountability function. They reveal disagreement that a single judgment might otherwise conceal and force the majority to respond to competing readings of text, history, precedent, or facts. A dissent can address the legal profession, elected officials, or future generations. That public dialogue may shape debate, but the authority to govern the present case remains with the controlling disposition.

A justice may dissent from only part of a decision. For example, the justice might agree that the plaintiff has standing but disagree with the majority's constitutional holding, or agree on liability but reject the remedy. Vote descriptions such as "concurring in part and dissenting in part" require the reader to separate each issue rather than attach one label to the entire opinion.

Keep the vote and the legal effect separate. A dissent disagrees with the judgment; a concurrence agrees with the judgment but gives different or additional reasons. Neither the eloquence of a dissent nor the number of citations it later receives permits a lower court to substitute it for a controlling holding. Its force is prospective and persuasive, not present and precedential.

When a question asks what lower courts must follow, the dissent is almost never the answer while a contrary majority holding remains controlling. When it asks which opinion preserves an alternative argument for future reconsideration, the dissent becomes directly relevant.

Video lesson: Judicial Decisions: Crash Course Government and Politics #22