Kangaroo court

A kangaroo court is a judicial tribunal or assembly that blatantly disregards recognized standards of law or justice, and often carries little or no official standing in the territory within which it resides. Merriam-Websterdefines it as a “mock court in which the principles of law and justice are disregarded or perverted“.[1] The term may also apply to a court held by a legitimate judicial authority who intentionally disregards the court’s legal or ethical obligations.

A kangaroo court is often held to give the appearance of a fair and just trial, even though the verdict has in reality already been decided before the trial has begun.

https://en.wikipedia.org/wiki/Kangaroo_court