Answer:
William Marbury most likely supported the Judiciary Act of 1789 because it allowed him to take his case to the Supreme Court. The Judiciary Act of 1789 established the federal court system and specifically granted the Supreme Court the power to issue writs of mandamus, which Marbury sought in order to compel Secretary of State James Madison to deliver his commission as a justice of the peace. Without this act, Marbury would not have had a legal avenue to pursue his claim in the Supreme Court.
The Judiciary Act of 1789 did not overrule James Madison or confirm Marbury's appointment, nor did it limit the Constitution's power to affect Marbury's case. Rather, it provided the legal framework for Marbury to bring his case before the Supreme Court and seek the relief he believed he was entitled to under the law.