Final answer:
Elizabeth Key, the daughter of a slave, was legally free because her father was a white, free man, which allowed her to petition for freedom based on her father's status.
Step-by-step explanation:
Elizabeth Key, the daughter of a slave, was legally free because Virginia laws stated that children born to enslaved women inherited the 'condition' of their mother. However, Elizabeth's father was a white, free man. This legal distinction allowed Elizabeth to petition for her freedom on the basis of her father's status. In a landmark court case in 1655, Elizabeth Key successfully sued for her freedom and the freedom of her child, establishing a precedent that children born to an enslaved mother and a free father were themselves free.