A Competition Law term applied to restrictions on the parties to an agreement or commercial relationship, which, while not core to the purpose of the agreement, are necessary for it to work effectively. An example might be a prohibition on parties to a joint venture competing directly with the joint venture or a post-sale non-compete on the vendor of a business. Ancillary restraints are usually strictly scrutinized and should be limited to what is strictly necessary (or vital) to make the transaction or business relationship viable.