The Lex Parliamentaria; or, A treatise of the law and custom of the Parliaments of England, was a pocket manual for members of the English Parliament. It was originally attributed to George Petyt. However, the attribution to Irishman George Philips

George Philips

Sir George Philips, 1st Baronet , later Sir George Philips MP.-Biography:Philips came from an old Staffordshire family that had held manors there since the reign of Edward VI of England, and were seated at Heath House in the same county since the early seventeenth century, that continued to be...

 seems now to be widely accepted, and attribution has also been claimed by both Sir James Ware

Sir James Ware

Sir James Ware was an Irish historian.-Early life:Born at Castle Street, Dublin, Ware was the eldest son of James Ware, who arrived in Ireland in 1588 as a secretary to Lord Deputy FitzWilliam. His father was knighted by King James I, was elected M.P...

 and Walter Harris

Walter Harris

Walter Edward Harris, PC, QC was a Canadian politician and lawyer.Harris was first elected to the Canadian House of Commons as the Liberal Member of Parliament for the Ontario riding of Grey-Bruce in the 1940 election defeating Agnes MacPhail...

. Thomas Jefferson

Thomas Jefferson

Thomas Jefferson was the principal author of the United States Declaration of Independence and the Statute of Virginia for Religious Freedom , the third President of the United States and founder of the University of Virginia...

 praised the book in a letter to his son-in-law, opining, "For parliamentary knowledge the Lex parliamentaria is the best book." Its American counterpart is the Lex Parliamentaria Americana by Luther Stearns Cushing. The "lex parliamentaria" is also sometimes used to describe parliamentary law in general.