Hello. Your question is incomplete and this makes it impossible for it to be answered. However, in the context of your question, we can assume that you are referring to John Marshall's decision regarding the Marbury v. Madison. If that is the case, I hope the answer below can help you.
Answer and Explanation:
In the case of Marbury v. Madison, John Marshall decided that the national congress does not have absolute power over government decisions, as, like the entire political body in the country, it was subject to the laws covered by the federal constitution. Thus, any act, adopted by Congress, or any other branch of government, that was unconstitutional, that is, that was not approved by any law within the federal constitution, could be revised or completely annulled by the Supreme Court.
What prompted Marshall to decide this was the positioning of the federal constitution as the country's supreme law, which cannot be violated in any way.
The Marbury case v. Madison, occurred when William Marbury, who was appointed as country judge by President John Adams, did not receive the diploma that allowed him to hold office, when James Madison became Secretary of State after President Thomas Jefferson came to power. However, as an appointed judge, Marbury had the right to receive the diploma and Marshall saw the denial of the diploma as an unconstitutional act.
