William H. Lamb, former Justice of the Supreme Court of Pennsylvania, is Chairman of Lamb McErlane PC and directs the firm's Post-Trial and Appellate Advocacy Group. Justice Lamb returned to the firm in January 2004, after serving a one-year appointment to the Supreme Court of Pennsylvania. Recognized as a top 100 Pennsylvania Super Lawyer for appellate law and a Pennsylvania Super Lawyer since 2005, he is the only former Pennsylvania Supreme Court Justice currently in practice.

Governor Mark Schweiker nominated Justice Lamb to the post in January 2003 to fill a vacancy created by the retirement of former Chief Justice Stephen A. Zappala. Justice Lamb was the first justice to serve from Chester County in 147 years, an achievement recognized in 2003 when he was named Citizen of the Year by the Chester County Chamber of Business and Industry.

During his tenure at Lamb McErlane, Justice Lamb served as a special prosecutor for Chester County from 1981 to 1984, during which time he received two Awards of Merit from the Pennsylvania State Police for his prosecution of the Johnston Brothers and Ancil Hamm cases. He served as District Attorney of Chester County from 1972 to 1980 and Assistant District Attorney in Chester County from 1967 to 1972.

Since returning to Lamb McErlane, Justice Lamb has put his experience to work for clients through a unique Mock Argument Service for attorneys preparing cases for appeal and argument. As part of the service, the Post-Trial group reviews the briefs, prepares a bench memo, and conducts an in-house conference. Justice Lamb then presides over the mock argument and questions counsel much as he did when he served on the bench. Thereafter, he discusses and critiques the argument at length and provides the parties with guidelines for arguing before the Court.

Justice Lamb is an active member of the community and is highly sought after for his political acumen on the federal, state and local levels. Since 2004, he has been appointed to the President's Advisory Committee on the Arts, the Commonwealth of Pennsylvania's Court of Judicial Discipline, and the Pennsylvania Elections Reform Task Force.