Jasper Yeates, born in Philadelphia, was once the most prominent lawyer in Lancaster County. He was a delegate to the state convention that ratified the U.S. Constitution, and served more than 20 years as a state Supreme Court justice.
Yeates earned a bachelor's degree from the College of Philadelphia in 1761, and shortly thereafter went on to study law. After his admission to the Pennsylvania Bar in 1765, he started his law practice in Lancaster.
In addition to his legal duties, Yeates served as captain in the Lancaster militia. Those duties were interrupted when the Continental Congress appointed him to a Commission of Indian Affairs to negotiate a treaty with the Lenape (Delaware) Indians at Fort Pitt. The commission's efforts resulted in the Treaty of Fort Pitt in 1778, which gave American soldiers the right to travel through Delaware territory.