If you refer to a court or a meeting as a kangaroo court, you disapprove of it because it is unofficial or unfair, and is intended to find someone guilty.
[disapproval]
kangaroo court in British English
noun
an irregular court, esp one set up by prisoners in a jail or by strikers to judge strikebreakers
kangaroo court in American English
US
Informal
1.
an unauthorized, irregular court, usually disregarding normal legal procedure, as one in a frontier region
2.
any tribunal in which judgment is rendered arbitrarily or unfairly
Word origin
said to be so named because its justice progresses by leaps and bounds
Examples of 'kangaroo court' in a sentence
kangaroo court
Time will pass and those who organised this kangaroo court will find themselves inthe dock.
Times, Sunday Times (2015)
I wish to defend them in the cultural kangaroo court they find themselves dragged into.