the relationship between the parties privy to the contract, i.e. those who are direct parties to it. Until the passing of the Contracts (Rights of Third Parties) Act 1999, English law did not permit parties not in a relationship of privity to sue on a contract. Thus, a third party benefited by a contract could not sue on it. The effect of the Act has been to substantially relax this rule. Scots law and other civilian systems recognise a jus quaesitum tertio.
Collins dictionary of law. W. J. Stewart. 2001.