Legal Definitions - four, rule of

The Rule of Four is a long-standing procedural practice of the U.S. Supreme Court that determines whether the Court will hear an appeal. For the Supreme Court to grant a petition for a writ of certiorari—meaning it agrees to review a lower court's decision—at least four of the nine justices must vote to do so. This rule allows a minority of justices to bring a case before the full Court for consideration, ensuring that cases with significant legal questions or potential constitutional implications can be heard, even if a majority of the justices might initially prefer not to take the case.

Here are some examples illustrating the Rule of Four:

• Example 1: Resolving a Conflict in Federal Law

  Imagine two different federal appellate courts (Circuit Courts) issue conflicting rulings on how a specific federal environmental regulation should be interpreted. This creates confusion and inconsistent application of the law across different regions of the country. A party affected by one of these rulings petitions the Supreme Court to resolve the conflict. Initially, only three justices see the urgency in taking the case, but after internal discussion, a fourth justice agrees that the "circuit split" needs resolution to ensure uniformity in federal law. Because four justices agree, the Rule of Four is met, and the Supreme Court takes the case to provide a definitive interpretation of the regulation, thereby settling the conflicting rulings.

• Example 2: Addressing a Significant Constitutional Question

  Consider a state that passes a controversial law significantly restricting free speech on social media platforms. A lower federal court upholds the law, leading to an appeal to the Supreme Court. Five justices might initially believe the case is not yet ripe for review or that the lower court's decision is sound enough. However, four justices are deeply concerned about the potential implications for First Amendment rights and believe the issue is of such national importance that the Supreme Court must address it. Despite the initial hesitation from the majority, the agreement of these four justices invokes the Rule of Four, compelling the Court to grant certiorari and hear arguments on the constitutionality of the state law.