Certificates of Freedom
One of the historical jobs Justices of the Peace would sometimes do in the course of their duties was to issue certificates of freedom. These were papers that black people would have to carry on them in many states to ensure that they would not be harassed as runaway slaves. Since this was pre-photography in many cases, there would be descriptions of the people carrying the papers to make sure that they were not using someone else’s certificate of freedom. Here is some more description of the process.