Hundreds of years before the Virginia case of Mildred and Richard Loving began the overturning of miscegenation laws, the Butlers of Maryland began to sue for their freedom and that of their heirs.

Under the rule of Charles Calvert, the third Lord Baltimore, Maryland enshrined the slavery of Blacks as a lifelong condition in a 1664 law declaring all negroes and other slaves in or brought to Maryland to be slaves for life. The law also defined the status of children of slaves as lifelong slaves and the fate of non-slaves who marry or have children with slaves. To discourage free English women from "disgracing our Nation", the law made white women who marry slaves the property of their husband's master for their husband's lifetime, and their children slaves for life. The children of these mixed marriages that were contracted before that 1664 act would be enslaved for thirty-one years. Oddly, the offspring of unmarried black men and white woman, as well as the offspring of any white man and black woman, were to be free.

In 1681, a 16-year-old Irish immigrant, Eleanor "Nell" Butler, who came to Maryland as an indentured servant to Charles Calvert, the third Lord Baltimore, was married in a Catholic ceremony by a priest to a slave known as Negro Charles at the home of Charles' enslaver, Major William Boarman in Charles County. Boarman's land grant came from his friend Charles Calvert who tried to dissuade Nell from marrying Negro Charles knowing that she would condemn herself and her heirs to a life of slavery. Nell married Charles and moved to the Boarman estate as a spinner and midwife.

Shortly after the wedding Lord Baltimore was influential in passing a 1681 law which repealed the 1664 statute and did NOT require the enslavement of white women and their children if their marriage was permitted or encouraged by their master.

Nell and Charles had eight children, all born after the repeal of the 1664 slave Law. Married before the new act took effect, the Butlers remained enslaved, and the Boarmans passed them and their heirs down as property from generation to generation.

The Butler family oral tradition repeated the story of Charles and Irish Nell. In 1770, the Butlers' grandchildren William and Mary, who were both directly descended from Nell Butler sued for their freedom. They were first cousins once removed and married. The repercussions of their freedom suit would affect potentially dozens of other slaveholders across the Western Shore of Maryland. Hundreds of other enslaved people in different families caught between the provisions of the 1664 and 1681 acts might make similar claims and bring lawsuits. Thousands might be liberated in the wake of this single decision.

The judges of the provincial court initially ruled in favor of freedom for William and Mary Butler nearly 89 years after their grandparents' marriage.

But Boarman's attorneys were quick to appeal the case to the highest appellate court in the colony. They argued that Nell and her children were property, and property could not be taken away by legislation "ex post facto" unless explicitly stated. A law, they concluded, cannot operate "on events antecedent to its passage."

Within a few months, the court of appeals reversed the lower court's ruling and denied the Butlers their freedom. The justices determined that the assembly of 1681 "knew that [property] rights had been acquired under the law of 1664, and in the course of so many years as that law subsisted, there might have been instances where these rights had been transferred." Although the General Assembly decided to repeal the 1664 act, the judges "thought it would be contrary to public faith to destroy these rights." Plainly speaking, slaveholders had property rights on the lives of children yet unborn, a claim they acquired through the 1664 act. The court would not "strip Boarman" of this property, nor would it interfere with the property rights of slaveholders who might have purchased slaves from Boarman. The right to the unborn children meant they all would continue to be enslaved.

William and Mary Butler died in slavery, however, the Butler family in Maryland changed the face of activism for enslaved people claiming their freedom, filing over 90 lawsuits for their freedom between 1787 and 1791. Approximately 129 Butler descendants were freed over the next 6 generations as a result of the lawsuits.