Legal Question in Civil Litigation in California

Conspiracy is not a cause of action, it is a form of vicarious liability. There is no such thing as a conspiracy to breach a contract, as conspiracy is a form of vicarious liability for torts, and not contracts. The tort name you are looking for is tortious interference with contract.

You actually have it backward. You cannot plead a civil action for conspiracy, but you CAN plead a cause of action for wrongful interference with a contract or other business relationship. It's a tough case to plead and prove, but it IS a valid cause of action against a third party who wrongfully induces a breach of contract. The tricky part is what constitutes "wrongful." Not every action that induces a breach is wrongful. For example, say you are in the widget industry and have a customer who has contracted for 120,000 widgets to be delivered and paid for in lots of 10,000 widgets per month for a year, with an option to renew for an additional year at a 2% price increase. Then your competitor develops the Super Widget 9000, that lasts twice as long and costs half as much. In month six of your contract, their salesman pitches the new product to your customer, and as a result the customer decides that even if they have to pay you breach of contract damages for canceling your contract, they will save money by switching to the SW9000. You don't have a case against your competitor. On the other hand, say the competitor just makes the same old widgets you do, but in month 10 your customer notifies you it is going to exercise the option, and then in month 11 the competitor's salesman comes in and says, if you cancel the contract we'll sell you widgets at under cost for the next year, if you agree to a two-year contract with the second year at a 4% increase. Your customer does the math and decides to cancel the renewal option. In that case, because pricing goods under cost in order to drive out a competitor is legally wrongful, you would have a case against your competitor for wrongful interference with your contract. You might even have a case if your customer had only notified you that they were pretty sure they were going to exercise the option, and just needed the CFO's signature on it. That could be "wrongful interference with prospective business advantage." So the bottom line is that inducing a breach is not always actionable, but if it is done via wrongful conduct, then no conspiracy needs to exist; you just sue for wrongful interference with contract.