In legal practice, an instrument is a formally executed document that creates, records, transfers or extinguishes legal rights or obligations. It typically refers to written agreements or declarations intended to have binding legal effect, such as deeds, contracts, wills, powers of attorney, guarantees, share certificates and negotiable instruments.Across England and Wales, Scotland, Northern Ireland and Ireland, the term is used broadly and contextually rather than having a single universal statutory definition. Specific legislation may define “instrument” for particular purposes (for example, in property, company, financial services or tax law), often to determine when a document must be in writing, executed as a deed, registered, or subject to stamp duty.Key legal features usually include: (i) a written document; (ii) executed or signed in the manner required by law; and (iii) intended to have legal effect on rights, title or obligations. In Scots law, “formal writing” and “probative” execution often overlap with the idea of an instrument.In practice, identifying whether a document constitutes an instrument affects enforceability, priority, registration, evidential status and formalities such as witnessing, delivery and electronic execution.