Both California contract law and tort law allow for legal action when a third party wrongfully interferes with a contract or ongoing business relationship. California Supreme Court Clarifies Pleading Requirements for Claims of Tortious Interference with AtWill Contracts.Click to share this page Any individual involved in business will likely have seen claims for interference with relationships, either prospective or contractual. The most powerful tool capable of invalidating competitive restraints under California law is Business and Professions Code section 16600. An actionable claim for interference with contractual relations does not require that the defendant have the specific intent to interfere with a contract. The federal circuits are divided over whether a claim for tortious in- terference with contract can be brought under section 301(a) of the Labor.