How to Prove Tortious Interference Under New York Law

Let's start at the beginning. Tortious interference is a closely related cousin of a breach of contract claim; it's not the same thing. This article will focus on the two types of tortious interference claims that are available under New York law - interference with prospective advantage, and interference with contract.

Interference With Contract - In order to prevail, the plaintiff claiming that the defendant interfered with an existing contract is required to show that the defendant not only knew about the plaintiff's contract with a third party, but that the defendant purposely - and without a good reason (in legalese, "justification") caused the third party to break its contract with the plaintiff.
Interference With Prospective Advantage - Unlike the interference with contract claim, this cause of action does not involve an already existing contract; it arises out of the defendant inducing the third party to walk away from a prospective contract, i.e., a contract that had not yet been finalized, with the defendant. Naturally, since this claim does not involve a finalized agreement, and therefore, the potential for abuse by overly litigious claimants with "questionable" proof of phantom agreements would in theory be rather great, the courts and legislature set the plaintiff's burden of proof on this claim signficantly higher than in the interference with contract realm.

Here, the plaintiff is required to prove not only that the defendant "intentionally and knowingly" induced the third party to act against the defendant (as is the case with interference with contract); the plaintiff must also prove that the defendant acted "by wrongful means," i.e., used "physical violence, fraud, misrepresentation or undue economic pressure" to prevent the third party from completing its contract with the plaintiff.

Thus, there is no question that the latter form of tortious interference claim is significantly more challenging to sustain than the former.