A Schnader appreciation of Mr. Shestack's work said that he was a founder of the American Bar Association's Pro Bono Center and a founder of the Public Interest Law Center of Philadelphia.
His son said Mr. Shestack was "a founding member and the first executive director of the Lawyers' Committee for Civil Rights Under Law," the first chair of the ABA Commission on the Mentally Disabled, and a chair of the ABA Standing Committee on Legal Aid.
Among his honors were the ABA Medal and the Gruber Foundation's Justice Award.