nihil obstat vs rubber stamp

nihil obstat

noun
  • A declaration of no objection; (specifically) a declaration used by the Catholic Church to indicate a book, initiative, or appointment to an office has been found to not breach religious or moral norms. 

rubber stamp

verb
  • To process, approve or decide matters routinely rather than through careful consideration. 

noun
  • A person or organisation that approves, routinely or as a formality, matters decided by some other person or organisation. 

  • A piece of rubber or similar material with a design or text carved or molded for the purpose of transferring ink or dye to imprint that design on another object. 

adj
  • Of a person, organisation, or process, making decisions or approving matters routinely or without real power. 

How often have the words nihil obstat and rubber stamp occurred in a corpus of books? (source: Google Ngram Viewer )