Thomas Jefferson served two terms as president. He spent much of his time fighting the Federalist agenda from the two previous administrations. He also found that even though he was a proponent of states's rights at heart, there were times when the federal government needed to stretch the bounds of the Constitution.

In 1807, Jefferson ended the foreign slave trade beginning January 1, 1808. He also established the precedent of executive privilege when he refused to testify in the Aaron Burr treason trial. Burr had been accused of trying to create an independent country within the United States that hinged on the taking of New Orleans. When Jefferson was subpoenaed by Burr's defense attorneys to provide documents, he refused on the premise that the executive branch was independent and that this action would go too far in usurping his power.

Fighting the Federalist Agenda

When Jefferson first took office, he had to deal with the midnight appointments from Adams's last hours in office. He immediately removed many of these officials from office. In the end, this led to the landmark Supreme Court Case, Marbury v. Madison (1803) in which the Judiciary Act, which allowed for Adams's last minute appointments, was ruled unconstitutional. This created the rule of judicial review that allowed the Supreme Court to rule laws unconstitutional.

Jefferson let the Alien and Sedition Acts expire. He also removed the tax on liquor that had caused the Whiskey Rebellion during Washington's presidency. The reduced revenue meant that Jefferson had to cut costs, including reducing the military, relying instead on state militias.

Fighting the Pirates

From 1801 to 1805, America engaged in a war with Tripoli. The United States had been paying money to pirates in the Barbary States, a group of North African states including Tripolitania and Morocco, to keep them from attacking American ships. Jefferson refused their demands for more money, and Tripoli declared war. The United States was able to defeat Tripoli but did have to continue paying tribute to pirates from other Barbary States.

Louisiana Purchase

Jefferson had a difficult decision to make in 1803 when he was offered the Louisiana Territory, an area comprising more than 529 million acres of land including parts or all of fifteen present day states. Napoleon offered it for the price of $15 million. Jefferson felt it important to possess this area, but at the same time he did not believe that the Constitution allowed him to take this action.

Not wanting to lose the deal, he went ahead and got Congress to authorize the expenditure. He then sent Meriwether Lewis and William Clark to explore the area.

Chesapeake and the Embargo Act

During Jefferson's second term, American trade ships were caught in the crossfire between warring France and Britain. The British practice of impressment — forcing sailors to work on their vessels — caused much contention. This came to a head when the British boarded the Chesapeake, impressing three sailors and killing one. In response, Jefferson signed the Embargo Act of 1807, which stopped all imports and exports of foreign goods. Jefferson hoped this would hurt France and Great Britain economically but instead it ended up hurting American trade. However, the fallout from this act would not be felt until the next president, James Madison, was in office, and would eventually be one of the causes of the War of 1812.