A swift witness is an expert witness who is instructed to give a focused, usually limited opinion on a discrete technical or professional issue, often to streamline or shorten proceedings. The term is descriptive rather than statutory, and is used most commonly in civil litigation and arbitration across England and Wales, Scotland, Northern Ireland and Ireland with broadly similar meaning.A swift witness is typically appointed where a full expert report under formal expert evidence rules (for example CPR Part 35 in England and Wales, or equivalent rules in the other jurisdictions) would be disproportionate, or where the court or tribunal directs tightly confined expert evidence on a particular point. Their role is usually narrower than that of a main expert, for example clarifying a single valuation assumption, a technical standard, or a short point of professional practice.Swift witnesses remain subject to the usual duties of independence and impartiality to the court or tribunal. In practice, they are used to reduce costs, avoid evidential overload and assist with focused case management, especially in commercial, construction and professional negligence disputes.