Both California contract law and tort law allow for legal action when a third party wrongfully interferes with a contract or ongoing business relationship. California Supreme Court Clarifies Pleading Requirements for Claims of Tortious Interference with AtWill Contracts.Click to share this page Our business litigation lawyers and attorneys have helped numerous businesses who have become victims of interference with contractual and business relations. Tortious interference refers to the action of a third party who causes harm to an ongoing business arrangement. California courts have long recognized causes of action for tortious interference with contract and tortious interference with prospective economic advantage. Tortious interference. When another business interferes with your business or contractual relationships causing economic damage. Proving to a court that a third party intentionally interfered in a business relationship or contract is complicated. Tortious interference with a contract involves situations where one party does something to intentionally undermine another party's business transactions.