Under Illinois law, a plaintiff cannot bring a cause of action for tortious interference against a party to the contract. In this article, we will explore what tortious interference with contract is, how to prove it, and how to protect your business against such a threat.A valid and enforceable contract between you and another party is required to recoup for tortious interfering with a contract. The following instructions are for use when there is a claim for tortious interference with an expectancy of an inheritance. The difficulty here is that you must prove that the defendant (or business rival) knew that there was a contract between client and the third party. What Elements Are Required to Prove Wrongful Interference? Proving to a court that a third party intentionally interfered in a business relationship or contract is complicated. In moving to dismiss Plaintiff's tortious interference with business relations claims, Defendants appear to misconstrue the complaint. Tortious Interference: This involves one party intentionally disrupting a contractual or business relationship, causing financial harm to another business. Proving to a court that a third party intentionally interfered in a business relationship or contract is complicated.