The Appellate Unit, under the leadership of District Attorney Mark Powell, represents the interests of the Commonwealth and its residents on appeals made from the Court of Common Pleas to the various state and federal appellate courts. These courts include the Superior Court of Pennsylvania, the Supreme Court of Pennsylvania, the U.S. District Court for the Middle District of Pennsylvania, the U.S. Court of Appeals for the Third Circuit, and the Supreme Court of the United States.

The purpose of the Appellate Unit is to ensure that justice is served on behalf of those who have already been involved in the criminal justice system. Its responsibilities include convincing the appellate courts, where appropriate, to uphold rulings and decisions by judges of the Court of Common Pleas, and the actions of prosecutors and law enforcement officers acting on behalf of the Commonwealth. The members of the Unit are required to research the law that governs the issues being appealed, drafting and submitting briefs and motions, and appearing before the appellate courts to make oral arguments before decisions are rendered. The Appellate Unit also appeals lower court rulings in cases where the District Attorney believes an injustice has been done.