On October 18, 1803, the Senate ratified a treaty with France, promoted by President Thomas Jefferson, which doubled the size of the United States. But was Jefferson allowed to make this $15 million deal in accordance with the Constitution? Monroe and Livingston immediately negotiated what Jefferson later called a „ephemeral event“, and on April 30 they reached an agreement that exceeded their authority – the purchase of louisiana territory, including New Orleans, for $15 million. The acquisition of approximately 827,000 square miles would double the size of the United States. Robert Livingston`s diplomatic breakthrough took place in April 1803 during the negotiations in Paris. At that time, the French were under enormous pressure, for they were on the verge of a war with Great Britain, which absolutely shook Napoleon. Talleyrand then turned to the two Americans to see what the price of the entire land mass would be. Robert Livingston and Monroe knew of France`s pressure and their ultimatum to cede the United Kingdom to the United States. That`s the way it is. Another concern was whether citizenship should be granted to the French, Spaniards and free blacks living in New Orleans, as stipulated in the treaty. Critics of Congress feared that these „foreigners,“ who do not know democracy, would become citizens.
The U.S. government had to use the English common law to make them citizens, to levy taxes.  At first, the situation was bleak, as Livingston`s first attempts to reach a diplomatic agreement failed. Early in 1803 Jefferson sent his young friend James Monroe from Virginia to Paris to help Livingston. Fortunately for the United States, Napoleon`s situation in Europe had changed at that time. The war between France and Great Britain was imminent and Napoleon could no longer spare the military resources necessary to ensure control of the territory of Louisiana. When Napoleon realized that the mighty British navy would probably take the territory by force, he argued that it was better to sell Louisiana to the Americans than to drop it into the hands of his enemy.