opening statement vs prologue

opening statement

noun
  • In adversarial legal systems, a statement made by a party at the beginning of a trial or comparable factfinding proceeding, in which that party lays out their case, generally including the points of fact that they intend to demonstrate and to some degree indicating the rhetorical arguments for why they should prevail. 

prologue

noun
  • A speech or section used as an introduction, especially to a play or novel. 

  • A component of a computer program that prepares the computer to execute a routine. 

  • One who delivers a prologue. 

  • An individual time trial before a stage race, used to determine which rider wears the leader's jersey on the first stage. 

verb
  • To introduce with a formal preface, or prologue. 

How often have the words opening statement and prologue occurred in a corpus of books? (source: Google Ngram Viewer )