When a contract disagreement cannot be resolved out of court, the complaining party will usually file a complaint in a state or federal court to start a lawsuit. In California procedure, the plaintiff lists in the complaint all reasonably possible legal theories of recovery, such as breach of contract, fraud and perhaps unjust enrichment. Legal procedure in all jurisdictions generally allows the listing of alternative claims in the complaint. It is left to the proof of the case to determine which of those theories, if any, will be applicable to provide relief.
There is a wide and unending subject matter of business disputes and types of businesses vying for finality in the civil court systems. The range goes from international business giants fighting over billion dollar disputes down to two small sole proprietorships pitted against one another. Of course, it often takes a relatively long time for a problem to become so intransigent as to require resort to the courts.