Tortious interference with contract—also known as intentional interference with contractual relations or business expectancy—is a civil claim or cause of action based on interference with a contract or a prospective contract that is about to be completed—by a person or entity who is not a party to the contract (third party).

A claim for tortious interference is based on the idea that the third party encouraged or induced one of the parties to the contract to breach the contract, causing damages to the nonbreaching party, who may sue the third party to recover those damages or losses. In some states there is a requirement that the interference be done maliciously or without justification.

Laws regarding claims for tortious interference with contract vary from state to state. Some states have broadened the protections against interference beyond situations where there is an existing contract and recognize claims for interference with prospective economic advantage or business relations.

But whether there is an existing contract or not, some instances of interference will not create legal liability and will be recognized as legitimate competitive activity, for example.

In Ohio, tortious interference with contract, also known as intentional interference with contractual relations, is recognized as a legal cause of action. To establish a claim for tortious interference, the plaintiff must prove the existence of a contract or business relationship, the wrongdoer's knowledge of the contract or relationship, the wrongdoer's intentional and improper act of interference, a breach or termination of the relationship or contract caused by the interference, and damages resulting from the interference. Ohio law requires that the interference must be intentional and without justification; mere accidents or unintended consequences do not typically give rise to liability. Ohio also recognizes claims for interference with business relations, which can apply to prospective economic relations even if no contract was yet in place. However, not all interferences are actionable. Acts of fair competition or legitimate business practices are not considered tortious interference in Ohio. An attorney can help determine whether a specific instance of interference may constitute a tortious act under Ohio law.