A dissenting opinion is a written statement by a judge who disagrees with the majority's decision. It does not change the outcome. The majority ruling stands. But dissents matter because they preserve arguments for the future and sometimes become the basis for later reversals.

Chief Justice John Marshall established the practice of a single majority opinion in the early 1800s. Before that, each justice wrote separately. Dissents became more common as the court's docket grew and the law became more complex. Some dissents are famous: Justice Harlan's dissent in Plessy v. Ferguson, Justice Holmes's dissent in Abrams v. United States, Justice Blackmun's dissent in Bowers v. Hardwick.

Types of dissents

• Pure dissent: disagrees with the result and the reasoning.
• Concurring in part, dissenting in part: agrees with some findings.
• Dissent without opinion: votes against but writes nothing.
• Per curiam dissent: brief and unsigned.

A dissent can signal that the issue is not settled. When the composition of the court changes, a previous dissent can become the new majority. That has happened repeatedly in constitutional law. Writing a dissent is an act of optimism about the future. It says the argument is not over, even if the vote is lost today.