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 Wisconsin, tortious interference with contract, also known as intentional interference with contractual relations, is recognized as a civil cause of action. This occurs when a third party, who is not part of an existing contract, intentionally and improperly interferes with the contract, inducing or causing one of the contracting parties to breach it, resulting in damages to the other party. The elements typically required to establish a claim in Wisconsin include the existence of a contract, the third party's knowledge of the contract, intentional and improper interference inducing or causing a breach, and resultant damage to the party whose contract has been breached. Wisconsin law also recognizes claims for interference with a prospective contract or business expectancy, which deals with interference in business relationships that are expected to culminate in a future contract. However, not all interferences are actionable; some are considered legitimate competitive behavior. The distinction often hinges on the presence of improper motives or means. An attorney can help determine whether a specific instance of interference may constitute a legal claim under Wisconsin law.