How does the US Supreme Court make decisions?

The Supreme Court justices vote to determine the outcome of a case. The decision is made when a simple majority (for example, five of the nine justices) agree on a judgment.


Most US Supreme Court cases are heard under the Court's appellate jurisdiction, whereby the issue was initially tried by the lower courts, has exhausted all avenues of appeal below the Supreme Court, and the losing party has petitioned the Supreme Court for a Writ of Certiorari. A petition for a Writ of Certiorari is a formal request that the Court review the final lower court appeal to determine whether questions of constitutional and federal law were interpreted and adjudicated correctly.

The Supreme Court does not conduct a trial under these circumstances, but reads the case history and lower court opinions, then listens to oral arguments on behalf of the Petitioner and Respondent (similar to a Plaintiff and Defendant) before determining whether the lower court decision was correct (affirmed) or incorrect (reversed). Because this level of appeal requires expert knowledge of constitutional precepts and laws, the nine Justices, alone, vote on the final decision.

Supreme Court cases are discussed in Conference three days after both the Petitioner and Respondent make oral arguments, and are then voted on by the full Court. The Chief Justice's vote carries no more weight than the Associate Justices' votes.

The Court's official decision is made by a simple majority vote of the justices involved in the case. Most often, a majority opinion is one where five or more of the nine Justices agree. If the vote is not unanimous, those in the minority may issue dissenting opinion(s); similarly, Justices who agree with the majority may issue concurring opinions if they wish to add points not covered in the official majority opinion.

For more information, see Related Questions, below.