In the case of Marbury v. Madison, Marshall simultaneously ruled that Madison had unjustly refused to deliver federal commissions to individuals who had been appointed by the previous administration, but that the Supreme Court did not have jurisdiction over the case. Most importantly, Marshall's opinion established the principle of judicial review.[142] While attaining the position of secretary of state and throughout his life, Madison's maintained contact with his father, James Sr., who died in 1801 and which allowed Madison to inherit the large plantation of Montpelier.[119]

The 1803 Louisiana Purchase totaled 827,987 square miles (2,144,480 square kilometers), doubling the size of the United States.
James Madison as Secretary of State painted by Gilbert Stuart, c. 1805–1807
Jefferson took office and was sympathetic to the westward expansion of Americans who had settled as far west as the Mississippi River; his sympathy to expansion was supported by his concern for the sparse regional demographics in the far west compared to the more populated eastern states, the far west being inhabited almost exclusively by Native Americans. Jefferson promoted such western expansion and hoped to acquire the Spanish territory of Louisiana, west of the Mississippi River, for expansionist purposes.