Two or three years before the Nebraska bill was thought of, a suit was begun by a negro named Dred Scott, in a local court in St. Louis, Missouri, to recover the freedom of himself and his family from slavery. He alleged that his master, one Dr. Emerson, an army surgeon, living in Missouri, had taken him as his slave to the military post at Rock Island, in the State of Illinois, and afterwards to Fort Snelling, situated in what was originally Upper Louisiana, but was at that time part of Wisconsin Territory, and now forms part of Minnesota. While at this latter post Dred Scott, with his master's consent, married a colored woman, also brought as a slave from Missouri, and of this marriage two children were born. All this happened between the years 1834 and 1838. Afterwards Dr. Emerson brought Dred Scott and his family back to Missouri. In this suit they now claimed freedom, because during the time of residence with their master at these military posts slavery was there prohibited by positive law; namely, at Bock Island by the ordinance of 1787, and later by the Constitution of Illinois; at Fort Snelling by the Missouri Compromise acts of 1820, and other acts of Congress relating to Wisconsin Territory. The local court in St. Louis before which this action was brought appears to have made short work of the case. It had become settled legal doctrine by Lord Mansfield's decision in the Somersett case, rendered four years before our Declaration of Independence, that "the state of slavery is of such a nature that it is incapable of being introduced on any reasons, moral or political, but only positive law.... It is so odious that nothing can be suffered to support it but positive law." The learned chief-justice therefore ordered that Somersett, being claimed as a Virginia slave brought by his master into England, when it was attempted to carry him away against his will, should be discharged from custody or restraint, because there was no positive law in England to support slavery. The doctrine was subsequently modified by another English chief-justice, Lord Stowell, in 1827, to the effect that absence of positive law to support slavery in England only operates to suspend the master's authority, which is revived if the slave voluntarily returns into an English colony where slavery does exist by positive law.