casuist vs informer

casuist

noun
  • A person who resolves cases of conscience or moral duty. 

  • One who is skilled in, or given to, casuistry. 

  • Someone who attempts to specify exact and precise rules for the direction of every circumstance of behaviour. 

informer

noun
  • A person who tells authorities about improper or illegal activity. 

  • One who informs, animates, or inspires. 

  • One who informs someone else about something. 

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