[Slang of U.S. origin.] An unfair, biased, or hasty judicial proceeding that ends in a harsh punishment; an unauthorized trial conducted by individuals who have taken the law into their own hands, such as those put on by vigilantes or prison inmates; a proceeding and its leaders who are considered sham, corrupt, and without regard for the law.
The concept of kangaroo court dates to the early nineteenth century. Scholars trace its origin to the historical practice of itinerant judges on the U.S. frontier. These roving judges were paid on the basis of how many trials they conducted, and in some instances their salary depended on the fines from the defendants they convicted. The term kangaroo court comes from the image of these judges hopping from place to place, guided less by concern for justice than by the desire to wrap up as many trials as the day allowed.
The term is still in common usage by defendants, writers, and scholars critical of a court or a trial. The U.S. Supreme Court has also used it. In in re gault, 387 U.S. 1, 87 S. Ct. 1428, 18 L. Ed. 2d 527 (1967), a case that established that children in juvenile court have the right to due process, the Court reasoned, "Under our Constitution, the condition of being a boy does not justify a kangaroo court." Associate Justice william o. douglas once wrote, "[W]here police take matters in their own hands, seize victims, beat and pound them until they confess, there cannot be the slightest doubt that the police have deprived the victim of a right under the Constitution. It is the right of the accused to be tried by a legally constituted court, not by a kangaroo court" (Williams v. United States, 341 U.S. 97, 71 S. Ct. 576, 95 L. Ed. 774 ).
kan·ga·roo court • n. an unofficial court held by a group of people in order to try someone regarded, esp. without good evidence, as guilty of a crime or misdemeanor.