Restatement (Second) of Torts

§ 766. Intentional Interference With Performance Of Contract By Third Person

One who

(1) intentionally and

(2) improperly

(3) interferes with the performance of a contract . . . between another and a third person

(4) by inducing or otherwise causing the third person not to perform the contract,

(5) is subject to liability to the other for the pecuniary loss

(6) resulting to the other from the failure of the third person to perform the contract.