The final authority over what? The answer to this question depends on the subject under discussion.
The final authority in the federal system is the Supreme Court.
Supreme Court
it acts as the final authority on the constitutionally of state and Federal Laws
the constitution
The Judicial Branch. The Supreme Court of the United States has the final authority over the interpretation of federal law.
U.s. constitution
The United States supreme court.
The Supreme Court.
The Supreme Court.
The Supreme Court has the ultimate say on whether something is constitutional or not.
Higher than the Court of Appeals is the Supreme Court. In the United States, the Supreme Court is the highest court in the federal judiciary system and has the final authority on matters of federal law and constitutional interpretation. State supreme courts serve a similar function at the state level, being the highest court in their respective jurisdictions.
The federal court system has three main levels: district courts (the trial court), circuit courts which are the first level of appeal, and the Supreme Court of the United States, the final level of appeal in the federal system.