• выгодоприобретатель – третье лицо – third party beneficiary
• третье лицо, в пользу которого заключен договор (должно быть произведено исполнение) – third party beneficiary
• третье лицо по делу – stranger to the proceedings
• третье лицо в судебной тяжбе – stranger to the litigation
• третье лицо, заявляющее самостоятельные требования относительно предмета спора – intervenor of right
• третье лицо, не заявляющее самостоятельных требований относительно предмета спора – permissive intervenor
См. также: требовать мирных переговоров, третейский судья, третья страна, трёхзвёздочная гостиница
Third Party. A generic legal term for any individual who does not have a direct connection with a legal transaction but who might be affected by it. (West's Encyclopedia of American Law, edition 2)
stranger
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5. (law) One not privy or party an act, contract, or title; a mere intruder or intermeddler; one who interferes without right. Actual possession of land gives a good title against a stranger having no title. (English Wiktionary)
STRANGER, persons, contracts. [...] 2. A person who is not privy to an act or contract; example, he who is a stranger to the issue, shall not take advantage of the verdict. (Law Dictionary of Legal Terminology)
A stranger to a contract cannot sue. A person may be a stranger to the consideration but he should not be a stranger to the contract because 'privity of contract' is essential for enforcing any of the rights arising out of the contract. It being a fundamental principle of the law of contracts that 'a stranger to a contract cannot sue, only a person who is a party to a contract can sue on it. (Study Package for CLAT & LLB)
A Third party or a stranger to a Contract cannot be added as a party to a Suit for Specific Performance. (indiankanoon.org)
intervenor: one who intervenes as a third party in a legal proceeding (Merriam-Webster Dictionary)
