Each year, the U.S. Supreme Court receives thousands of requests to review lower court decisions, but it agrees to hear arguments in only a small fraction of them, typically somewhere between 60 and 80 cases per term. Understanding how the Court chooses matters almost as much as understanding what it ultimately decides.

Most cases arrive through a petition for certiorari

The primary way a case reaches the Supreme Court is through a petition for a writ of certiorari, commonly shortened to "cert." A party that lost in a lower federal appeals court, or in a state's highest court on a federal legal question, can ask the Supreme Court to review that decision. The petition explains why the Court should take the case, and the opposing party typically files a response arguing it shouldn't.

The "rule of four"

Deciding whether to grant certiorari requires the agreement of at least four of the nine justices -- a long-standing internal practice known as the rule of four. This threshold, lower than the majority needed to actually decide a case, is intended to ensure that a determined minority of justices can bring an important issue before the full Court, rather than requiring majority agreement just to hear arguments in the first place.

What makes the justices more likely to take a case

  • A circuit split: When different federal appeals courts have reached conflicting conclusions on the same legal question, the Supreme Court often steps in to resolve the inconsistency and establish a uniform national rule.
  • A significant constitutional question: Cases raising novel or unsettled constitutional issues are more likely to draw the Court's attention than routine factual disputes.
  • Government involvement: Petitions filed by the U.S. Solicitor General's office, which represents the federal government before the Court, are granted at a notably higher rate than petitions generally.
  • Conflict with Supreme Court precedent: Cases where a lower court's ruling appears to depart from existing Supreme Court decisions can prompt review.

The role of law clerks and the "cert pool"

Because the volume of petitions is so large, justices rely heavily on law clerks -- recent law school graduates who work for the Court for a year or two -- to help review and summarize petitions. Many justices participate in a shared system known as the "cert pool," in which clerks from participating chambers divide up petitions and write joint memos summarizing each case for all participating justices, though some justices review petitions independently rather than through the pool.

What happens once cert is granted

Once the Court agrees to hear a case, both sides submit detailed written legal arguments called briefs, often supplemented by "friend of the court" briefs from outside organizations offering additional perspectives. The Court then typically hears oral argument, a relatively short session -- usually about an hour -- where each side's attorneys answer questions directly from the justices. A written opinion, sometimes accompanied by dissenting or concurring opinions from justices who disagree with parts of the reasoning or outcome, is usually issued months later.

Why so few cases are actually heard

The Supreme Court is not a general court of appeals meant to correct every lower court error -- its modern role, largely by design and practice, is to resolve significant, recurring legal questions rather than simply reviewing whether a particular case was decided correctly by the standards of existing law. This selective approach means the vast majority of petitions are denied without any explanation, leaving the lower court's decision in place, and the fact that the Court declined to hear a case is not treated as an endorsement of the lower ruling.