John Quincy Adams requested the Pinckney Plan from Charles Pinckney, but Pinckney said he didn't have it. He provided the Plan to John Quincy Adams, as best he remembered it. At that time, he retired from public life.
In 1819, Pinckney was elected to the U.S. House of Representatives. The Missouri Compromise issue came up before Congress. Missouri wanted to come in as a slave state, which would upset the balance in the U.S. Senate, which had an equal balance of slave states and free states. Pinckney was opposed to the idea that the federal government could in any way interfere with slavery or with that aspect of a state's power. Pinckney stated that this was not the intent of the Founding Fathers. The compromise was that Missouri would be admitted as a slave state, and that Maine would be admitted as a free state, maintaining the balance in the Senate. In addition, a provision was included that a line be drawn along the Southern border of Missouri, creating two corridors, in effect, one to the South in which slave states could be created, and one to the North in which slavery was prohibited.