Final answer:
A Supreme Court decision supported by five or more justices is known as a majority opinion, which provides the legal reasoning for the Court's ruling and sets precedent.
Step-by-step explanation:
A decision of the Supreme Court in which five or more justices agree on which party to the dispute should win the case and agree on the reason that party should win is known as a majority opinion. The majority opinion articulates the collective reasoning and legal foundations for the Court's decision, and at least five of the nine justices must agree to form this majority. In cases where a justice concurs with the outcome but not the rationale, they may write a concurring opinion. Justices not in agreement with the majority opinion may provide their reasoning in a dissenting opinion, which can influence future legal arguments and case law. The Supreme Court is the final court of appeal, deciding the remedy and resolution of the case, underscoring the supreme role of the judiciary in the American legal system.