The Missouri Compromise was a United States federal statute devised by Henry Clay. It regulated slavery in the country's western territories by prohibiting the practice in the former Louisiana Territory north of the parallel 36°30′ north, except within the boundaries of the proposed state of Missouri. The compromise was agreed to by both the pro-slavery and anti-slavery factions in the United States Congress and passed as a law in 1820, under the presidency of James Monroe.The Missouri Compromise was effectively repealed by the Kansas–Nebraska Act, submitted to Congress by Stephen A. Douglas in January 1854. The Act opened Kansas Territory and Nebraska Territory to slavery and future admission of slave states by allowing white male settlers in those territories to determine through ""popular sovereignty"" whether they would allow slavery within each territory. Thus, the Kansas–Nebraska Act effectively undermined the prohibition on slavery in territory north of 36°30′ latitude which had been established by the Missouri Compromise. This change was viewed by Free Soilers and many abolitionist Northerners as an aggressive, expansionist maneuver by the slave-owning South, and led to the creation of the Republican Party.Although already superseded by the Kansas–Nebraska Act, the Supreme Court indicated that the Missouri Compromise was unconstitutional in the 1857 Dred Scott v. Sandford ruling.