Contract law: Rights of third parties - Third-party beneficiary + Delegation + Novation

A third-party beneficiary, in the law of contracts, is a person who may have the right to sue on a contract, despite not having originally been an active party to the contract. This right, known as a ius quaesitum tertio, arises when the third party (tertius or alteri) is the intended beneficiary of the contract, as opposed to a mere incidental beneficiary (penitus extraneus). It vests when the third party relies on or assents to the relationship, and gives the third party the right to sue either the promisor (promittens, or performing party) or the promisee (stipulans, or anchor party) of the contract, depending on the circumstances under which the relationship was created.

A contract made in favor of a third party is known as a "third-party beneficiary contract." Under traditional common law, the ius quaesitum tertio principle was not recognized, instead relying on the doctrine of privity of contract, which restricts rights, obligations, and liabilities arising from a contract to the contracting parties (said to be privy to the contract). However, the Contracts (Rights of Third Parties) Act 1999 introduced a number of allowances and exceptions for ius quaesitum tertio in English law. Other common-law countries are also making reforms in this area, though the United States is unique in abandoning privity early in the mid-19th century.

In contract law and administrative law, delegation (Latin intercessio) is the act of giving another person the responsibility of carrying out the performance agreed to in a contract. Three parties are concerned with this act - the party who had incurred the obligation to perform under the contract is called the delegator; the party who assumes the responsibility of performing this duty is called the delegatee; and the party to whom this performance is owed is called the obligee.

Novation, in contract law and business law, is the act of –

1.    replacing an obligation to perform with another obligation; or

2.    adding an obligation to perform; or

3.    replacing a party to an agreement with a new party.

In international law, novation is the acquisition of territory by a sovereign state through "the gradual transformation of a right in territorio alieno  into full sovereignty without any formal and unequivocal instrument to that effect intervening".