Why can lower federal and state courts decide constitutional questions?

In the United States, all lower federal and state courts possess the authority to decide constitutional questions because they are obligated to determine the validity of statutes or executive actions whenever such issues arise in the course of deciding a case before them.1

This power is rooted in the principle that it is the duty of the judiciary to interpret the law. As established in the landmark Supreme Court decision Marbury v. Madison (1803), the Constitution is the supreme law of the land, and any legislative act repugnant to it must be controlled by it. Because courts must apply the law to particular cases, they must necessarily expound and interpret that law, including determining whether a statute or action is consistent with constitutional principles.12

While lower courts are empowered to engage in this judicial review, their decisions are subject to appellate review. Ultimately, the U.S. Supreme Court serves as the final arbiter when a federal or state statute is challenged as violating the U.S. Constitution.13