Rogatory letters (letters rogatory; often called a letter of request in UK practice) are a court‑to‑court request for judicial assistance in another country, typically to take evidence, serve proceedings, or carry out a step for use in litigation.The term is descriptive rather than defined, with operation governed by treaties and domestic statutes. In England & Wales, Scotland and Northern Ireland, civil evidence requests to and from abroad are dealt with under the Hague Evidence Convention 1970 and the Evidence (Proceedings in Other Jurisdictions) Act 1975; outgoing requests are made under CPR 34 and equivalent Scottish/NI rules. The courts will not order wide, discovery‑style fishing expeditions: see the State of Norway applications. Execution is according to the requested state’s law, subject to privilege and public policy, and may require translations, specific questions and payment of expenses.In criminal matters, assistance is channelled through mutual legal assistance (UK: Crime (International Co‑operation) Act 2003; Ireland: Criminal Justice (Mutual Assistance) Act 2008), though the terminology persists.Ireland follows the Hague Evidence Convention and, intra‑EU, the EU Evidence Regulation (Regulation (EU) 2020/1783). For service abroad, the UK and Ireland use the Hague Service Convention; rogatory letters are used where no treaty route exists.