court of inquiry vs kangaroo court

court of inquiry

noun
  • A judicial assembly that is created to investigate and rule on a specific incident. 

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 court of inquiry and kangaroo court occurred in a corpus of books? (source: Google Ngram Viewer )