noun
1. : a mock court in which the principles of law and justice are disregarded or perverted:
a. : one held by vagabonds or by prisoners in a jail or prison camp
kangaroo courts … are vicious organizations controlled by the most perverted and brutal prisoners — J.V.B.Bennett
non-Communist prisoners sentenced to death by Red kangaroo courts — Army-Navy-Air Force Journal
b. : one involving comic procedures and ludicrous penalties designed for the amusement of the participants and spectators
kangaroo courts — to which anyone not in Western garb can be hauled and find — Helen Gould
2. : a court or a similar body (as a legislative investigating committee) characterized by irresponsible, unauthorized, or irregular status or procedures
in Czechoslovakia … kangaroo courts have been handing down stiff sentences for “labor sabotage” — C.L.Sulzberger
two committee jobs which put him … in the position of conducting his own kangaroo court — Atlantic