Commonwealth v. Aves decision establishes that enslaved persons brought into Massachusetts must be freed.

The case is is brought by attorney Ellis Gray Loring on behalf of six-year-old Med , an enslaved girl brought to Boston by her enslave Mary Slater, on a visit to her father, Thomas Aves. In his decision, chief justice Lemuel Shaw establishes the so-called Freedom Principle, declaring “All persons coming within the limits of a state [are] entitled to the privileges which those laws [of the state] confer . . . this rule applies as well to blacks as white.” However, the ruling not apply to fugitive enslaved persons, who make their way to Massachusetts on their own.