 When Robert Livingston approached France in 1803 about buying the Isle of Orleans, the French government offered to sell it and all of Louisiana as well.While the purchase of Louisiana exceeded their authorization, Livingston and James Monroe (who had been sent to help him negotiate the sale) in the deliberations with France pursued a claim that the area east of the Mississippi to the Perdido River was part of Louisiana.As part of the 1803 Louisiana Purchase treaty, France repeated verbatim Article 3 of its 1800 treaty with Spain, thus expressly subrogating the United States to the rights of France and Spain.p.