A grant of certiorari is a docket decision, not a decision on the merits. Four justices might vote to hear a case because federal courts of appeals have adopted conflicting rules, a lower court has decided an important federal question, or existing Supreme Court doctrine needs clarification. After full briefing and oral argument, some of those four may reject the petitioner's position, and other justices may supply the majority. A case granted by four votes can therefore end in a lopsided judgment against the party that requested review.

The practice protects minority access without giving four justices power to decide the case. Five colleagues cannot always keep an issue off the docket merely because they currently prefer the lower-court result, yet the four who vote to hear still must persuade enough justices on the merits. That design separates the institutional value of clarification from agreement with a litigant's argument.

Votes on certiorari are not ordinarily accompanied by a full public explanation. A justice may sometimes write about a denial, but readers usually cannot know why each justice voted as they did. That is another reason denial lacks precedential meaning. It can reflect vehicle problems, timing, workload, or a desire for further lower-court development rather than approval of the judgment below.

Keep three numbers and actions separate: four votes can ordinarily grant review; a majority ordinarily controls the Court's judgment when all nine participate; and denial of certiorari carries no implication that the Court approves the lower court's reasoning. The Rule of Four is not found in Article III and does not create a right to Supreme Court review. It is an internal practice governing the Court's largely discretionary appellate docket.

A CLEP distractor may say that four votes invalidate a statute or establish precedent. Four votes open the door to review. The judgment and controlling opinion come later through the merits process.

Video lesson: Supreme Court of the United States Procedures: Crash Course Government and Politics #20