Legal instrument is a legal term of art that is used for any formally executed written document that can be formally attributed to its author, records and formally expresses a legally enforceable act, process, or contractual duty, obligation, or right, and therefore evidences that act, process, or agreement. Examples include a certificate, deed, bond, contract, will, legislative act, notarial act, court writ or process, or any law passed by a competent legislative body in municipal (domestic) or international law. Many legal instruments were written under seal by affixing a wax or paper seal to the document in evidence of its legal execution and authenticity. However, today many jurisdictions have done away with the requirement of documents being under seal in order to give them legal effect.

कानूनी लिखत का प्रचलित तात्पर्य है, कानूनी दस्तावेज जो किसी अधिकार को प्रदान करता है या उसकी पुष्टि करता है या सच्चाई का लेखा-जोखा रखता है। यह किसी भी तरह का व्यावहारिक लेख होता है जैसे कि : कोई करारनामे का दस्तावेज या लेखा-जोखा जो कि तकनीकी रूप से तैयार व प्रस्तुत किया गया हो।