In Malinda Fox v. The State of Ohio, the Supreme Court heard a case concerning an African American woman's right to freedom from slavery in the state of Ohio. Malinda Fox had been born into slavery and was later sold by her master to another man who took her out of state for several years before returning with her to Ohio. Upon their return, she argued that since she had been taken out of the state for so long, she should be considered free under a provision in the Northwest Ordinance which stated that any slave brought into a free territory would become emancipated upon arrival there. The court ultimately ruled against Ms. Fox on technical grounds; they found that while it was true that slaves were freed when entering free territories according to law, this did not apply if they left those territories again and returned at some point afterwards as Ms. Fox had done here.

In the case of Malinda Fox v. The State of Ohio, the Supreme Court was asked to determine whether a state law that prohibited African Americans from testifying against white persons in criminal cases violated the privileges and immunities clause of Article IV Section 2 of the United States Constitution. Justice McLean delivered a dissenting opinion arguing that while he did not believe it was within his power to decide on matters concerning slavery or emancipation, he believed that this particular law deprived African Americans of their constitutional rights as citizens by denying them equal protection under the law. He argued further that such laws were contrary to public policy and should be declared unconstitutional because they denied individuals basic civil liberties regardless of race or color.