court martial vs kangaroo court

court martial

noun
  • A trial before such a tribunal. 

  • A court where cases of military law are heard. 

verb
  • To subject to trial in a military court. 

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