Tortious interference, sometimes also known as intentional interference with contractual or business relations, is a common law tort claim. Tortious interference falls under common law tort.Tortious interference happens when your competitor tries to break or damage an economic agreement or contract your business has with a third party. A Standard Clause providing model language that a plaintiff can use to plead a claim for tortious interference with contract under Pennsylvania law. The Law Offices of Stanley B. Cheiken offers skilled representation in tortious interference disputes. Pennsylvania Supreme Court Opens Door for Terminated AtWill Employees to File Tortious Interference Claims Against Third Parties. Philadelphia Electric Company. Jeffrey P. Lewis is a member in the Philadelphia office of the law firm of Eckert Seamans Cherin. (5) For prospective contracts, a reasonable likelihood that the relationship would have occurred but for the defendant's interference. Interference claims require that the victims are involved in a legal contract or have a business relationship.