What does the judicial branch do?

Why this is the answer

The judicial branch reviews laws, explains laws, resolves disputes about the law, and decides whether a law goes against the Constitution. The official list accepts any one of those four. All four describe a single job. The Constitution is the supreme law of the land, so every law Congress writes has to fit within it. Someone who believes a law does not fit can bring a case to a federal court and challenge it. The court then interprets the law, settles the disagreement, and, if the law conflicts with the Constitution, declares it unconstitutional and rejects it. The Supreme Court has the final say on cases involving federal laws and treaties, and it also hears other kinds of disputes, such as disagreements between states. There is an important limit. Courts do not go looking for laws to review. A federal court can rule on a law only when a legal case is brought before it and the court has the authority to hear that case. Alexander Hamilton made the argument for this role in Federalist No. 78. Interpreting the laws, he wrote, is "the proper and peculiar province of the courts," and when a statute and the Constitution cannot be reconciled, judges must prefer the Constitution. The Supreme Court established the power, known as judicial review, in Marbury v. Madison. It has used it on questions that affect the whole country; its decision in Brown v. Board of Education of Topeka ended racial segregation in schools. Wrong answers usually borrow the work of another branch. "Makes laws" belongs to Congress, so it cannot be right here, and neither can anything about commanding the military or declaring war. If the four official phrases blur together under pressure, "reviews laws" is the shortest and the easiest to say. A good way to remember the list is to follow a case through court: the judge explains what the law means, settles the dispute in front of the court, and checks the law against the Constitution, which is what reviewing it means.