German families in the New Orleans area claimed that Sally was in fact the child of immigrants who had died and that the girl was subsequently indentured by an unscrupulous owner and later sold into slavery. The main question raised by the piece is whether Sally really was a German girl or whether she was just a clever slave who was grabbing at her once chance for freedom.
The fact that the color of a person's skin was the basis of whether they could be enslaved or not shows the racism that was at the heart of this culture. It is fascinating that the case revolved around the fact of whether Sally was German, and thus not deserving of slavery rather than the fact that slavery was morally objectionable per se.
The idea that color and slavery were indelibly linked was starting to be threatened by the inter-breeding that had been occurring between slaves and whites for generations. By this time, just a decade before the American Civil War would end slavery, many slaves looked as white as their masters. Thus the very basis of slavery - the supposed inferiority of black races - was called into question by the continuum of color that then existed in America.
The lack of certainty as to race was reflected within the legal system, in which slaves were regarded as property and yet, paradoxically, could also have legal representation within trials. Thus if a slave was accused of murder he/she had the right to legal representation, although as the author shows, the degree to which this right was enforced depended very much upon individual circumstances and the judge who was available.
Bailey essentially shows a society that is ripe for change. The mysterious origin of Sally Miller reflected the complexity of race that was characteristic of America by the mid nineteenth-century. The simple duality of "slave" and "master" was increasingly being challenged on an ethical and legal basis. Slaves could buy their freedom and many tried to make their way to Northern states where slavery was already abolished. The idea that the identity of a person was set as "slave" or "non-slave" is shown to be too simplistic by the case of Sally Miller. If Miller was indeed of German origin, then a person could move from non-slave to slave because of bad luck and unethical businessmen. If a slave was lucky, earned enough money or had an enlightened master, he could become a non-slave.
To conclude, the fact that the case was never resolved in a concrete manner shows the history is often not as certain as many people would like. The actual origin of Sally Miller will probably never be known now, any more than it was proved in the court case. What emerges is the terrible manner in which immigrants were treated in America at this time, even those from supposedly privileged countries such as Germany. The book also shows the complex legal environment of America at the time, and gives a view of the legal position of slaves that has seldom been considered before. Ultimately the book shows the mystery of human nature and identity, especially racial identity. If a slave is more white than her master, what is the basis for the slavery if it is based upon the supposed superiority of whites over blacks The answer was that slavery was based upon cruelty and exploitation rather than any rationally identified differences between races.