Definition of "by the book"

by the book

prepositional phrase
1. (idiomatic) In a manner which adheres strictly to rules, legal requirements, or official procedures.
  Quotations
  As far as he is concerned, he umpired by the book.
  2006 August 27, Simon Robinson, “It's Not Just Cricket”, in Time
2. (idiomatic, by extension) In a manner which appears too studied, ritualized, and therefore artificial.
  Quotations
  Romeo: Sin from thy lips? O trespass sweetly urged!Give me my sin again.They kiss again.Juliet: You kiss by th' book.
  c. 1591–1595 (date written), William Shakespeare, “The Tragedie of Romeo and Ivliet”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act I, scene v]