courtroom vs kangaroo court

courtroom

noun
  • The room where a judge presides over hearings and trials, sometimes with a jury. 

kangaroo court

noun
  • A judicial or quasi-judicial proceeding, or a group of people which conducts such proceedings, which is without proper authority, and often acts abusively or decides unjustly. 

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