Erskine May (full title: Erskine May: Parliamentary Practice, original title: A Treatise upon the Law, Privileges, Proceedings and Usage of Parliament) is a parliamentary authority originally written by British constitutional theorist and Clerk of the House of Commons, Thomas Erskine May (later the 1st Baron Farnborough).Erskine May is considered to be the most authoritative and influential work on parliamentary procedure and the constitutional conventions affecting Parliament which form a major part of the uncodified UK constitution. It is not a rigid set of rules but a description of how the procedure evolved and of the conventions. Such is the authority of the text that it is regarded as analogous to part of the constitution itself.Since its first publication in 1844, the book has frequently been updated. Erskine May edited nine editions of the book in his lifetime. Updates have continued into the present day; the 25th edition was published on 28 May 2019. The Speaker's Commission on Digital Democracy recommended in 2015 that "Erskine May, the definitive guide to parliamentary procedure, should be freely available online by the time the next edition is produced." This took effect in July 2019 with the 25th edition.The work has been influential outside the United Kingdom, particularly in countries that use the Westminster system. Source: Wikipedia (en)