Final answer:
The Judiciary Act of 1801, passed in the last days of John Adams' presidency, created new judgeships filled by "Midnight Judges" and reduced the number of Supreme Court justices to prevent Thomas Jefferson's appointments. It led to the landmark case Marbury v. Madison, which established judicial review.
Step-by-step explanation:
Judiciary Act of 1801
The Judiciary Act of 1801 is a significant legislative act passed during the last days of President John Adams' administration. This act was an attempt by the outgoing Federalist majority in Congress to maintain influence within the judiciary branch following the election of Thomas Jefferson, a Democratic-Republican. The act created new judgeships, including twenty-three new district and circuit court positions, which allowed the Supreme Court justices to be relieved from hearing district court cases. President Adams filled these new positions with Federalist supporters, who became known as "Midnight Judges" due to the last-minute nature of their appointments. Moreover, the act reduced the number of Supreme Court justices from six to five in an effort to prevent President-elect Jefferson from appointing a new justice. One of the most significant appointments was that of John Marshall as the Chief Justice of the Supreme Court.
However, not all commissioning documents for these appointments were delivered before the end of Adams' term, leading to conflict in the new administration. Thomas Jefferson's Secretary of State James Madison refused to deliver the remaining commissions. This resulted in the landmark Supreme Court case of Marbury v. Madison, which firmly established the principle of judicial review by ruling the Judiciary Act of 1789 unconstitutional in respect to granting the Supreme Court the power to issue writs of mandamus in original jurisdiction cases.