The Quock (spelled Quack in some documents) Walker cases were three related cases from 1781 to 1783, culminating in Commonwealth v. Nathaniel Jennison. They began with the imprisonment of Quock Walker by Nathaniel Jennison in 1781 and were the most famous slave cases prior to the Dred Scott decision in 1857. James Caldwell of Worcester, Massachusetts, purchased Quock Walker and his parents in 1754. When Caldwell died, Quock Walker went to Caldwell’s wife, who then married Nathaniel Jennison. When she died, Jennison believed the enslaved man was his property.