Marbury v. Madison is a very important court case that happened a long time ago in history. It all started when a man named William Marbury was appointed to serve as a judge by the previous president, John Adams. However, the person responsible for delivering the appointment letter, James Madison, didn't do it. This made Marbury very upset.
Marbury wanted to sue Madison so that he could get his job as a judge. However, he didn't know where to go to get help. He decided to go to the Supreme Court, which is the highest court in the land. The Supreme Court is like the king of all courts and judges.
The Supreme Court had to decide if Marbury's case was something they could handle. They decided that they did not have the power to make Madison deliver the letter. However, they also decided that a part of the law that gave them that power was unconstitutional. This meant that the law went against what the Constitution says, which is like the rule book for the country.
This was a big deal because it was the first time the Supreme Court said that a law was unconstitutional. It also established a principle called judicial review which means that the Supreme Court has the power to review laws to see if they are constitutional or not. This was a really important moment in history because it helped balance the power between the different branches of government and the significance is still felt today since judicial review continues to be an important aspect of America's democracy.