A compellable witness is a person who can lawfully be required, by witness summons or citation, to attend court and answer questions. In practice, most witnesses are compellable, but not all.
Compellability is a procedural concept recognised in statute and case law across criminal and civil proceedings. In criminal cases, the accused is not compellable for the prosecution and cannot be forced to give evidence; a co‑accused’s compellability is also restricted. Spouses and civil partners are generally not compellable for the prosecution except where legislation makes them so for specified offences, typically involving violence, abuse or sexual offences against the spouse or a child. The detail varies by jurisdiction and practitioners should check the governing provisions (for example, PACE 1984 s.80 in England and Wales, the Criminal Procedure (Scotland) Act 1995, the Criminal Evidence (Northern Ireland) Order 1999, and the Criminal Evidence Act 1992 in Ireland). In civil proceedings, parties and other witnesses are usually compellable, subject to recognised privileges.
Even a compellable witness may refuse to answer where a valid privilege applies (legal professional privilege, privilege against self‑incrimination where not abrogated, or public interest immunity). Compellability matters for obtaining and enforcing a witness summons; non‑compliance may lead to contempt or a...