In April 1846, the Scotts filed petitions with the state circuit court in St. Louis seeking their freedom. A combination of factors undoubtedly induced them to act when they did. Harriet Scott gave birth to the couples second child, a daughter, in April 1846. Working conditions may have worsened for the Scotts as they faced this new responsibility. They may also have been aware and fearful of the ardent proslavery sentiments of John Sanford, brother and financial advistor of their owner, Irene Emerson. When Sanford married Emilie Chouteau, the daughter of Pierre Chouteau Jr, he joined one of the oldest and wealthiest French families in St. Louis. The Chouteaus were also one of the largest slave holding families in St. Louis. Sanford also became a vocal defender of slavery and an advocate of strict enforcement of state laws limiting the liberty of free blacks. In this restrictive climate, the Scotts may have worried about losing one or more of their children in the slave trade.
Two men may have provided the Scotts with additional motives to sue. One was John R. Anderson, a free black man, who had worked as a typesetter in St. Louis before he moved with the antislavery editor Elijah P. Lovejoy to Alton, Illinois. When Lovejoy was killed by an antiabolitionist mob in 1837, Anderson returned to St. Louis where he led a congregation of black Baptists that included Harriet Scott. The second man was Francis Murdoch, a lawyer, who served as state prosecutor in the Alton trial of Lovejoys killers. After the jury acquitted the killers, Murdoch moved to St. Louis. It was Francis Murdoch who drafted and filed the Scotts petition for freedom
Before the Scotts case came to trial in June 1846, Murdoch left St. Louis for California. Another lawyer, Charles Drake, assumed responsibility for preparing the case for trial. Drake was the husband of Martha Ella Blow, the daughter of Dred Scotts first owner, Peter Blow. Why did the family of Dred Scotts former owner support his suit for freedom? The answer probably lies in the involvement of the oldest of the Blow children, Charlotte. When Peter Blow died in 1832 (his wife had died less than a year earlier) Charlotte, then twenty, assumed responsibility for the upbringing of her two young brothers. Charlotte had married Joseph Charless Jr in 1831 and he financed the Blow boys education and later brought them into his business as partners. Of the Blow children only Charlotte could have known Dred Scott well. When Murdoch left St. Louis, Scott may have appealed to Charlotte for assistance. In any case, Charolotte undoubtedly persuaded her brothers to provide financial support so that the Scotts could continue their litigation. It was probably she who prevailed on her brother-in-law, Charles Drake, to finish the work that Murdoch had begun. Whatever the motives of the participants, the court records leave no doubt that the Blow family provided the Scotts with financial support. With this help the Scotts managed to overcome legal technicalities and the delaying tactics of Irene Andersons attorneys and win their case. In January 1850 a St. Louis jury found in favor of Dred and Harriet Scott. In February 1850 Irene Emerson appealed that decision to the Missouri Supreme Court.