Prejudicial bias of the decision-maker or from political decree are among the most publicized causes of kangaroo courts. Such proceedings are 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. An example is the trial of Pol Pot and his brother Ieng San by the People's Revolutionary Tribunal in Cambodia in August 1979. After a lengthy trial with a duration of five days, both were sentenced to death in absentia on August 19, 1979. Conclusive evidence showed that the verdicts and the sentencing papers had been prepared in advance of the trial. Relying on this evidence the United Nations proceeded to delegitimize the tribunal stating that it did not comply with standards of international law.
A kangaroo court could also develop when the structure and operation of the forum result in an inferior brand of adjudication. A common example of this is when institutional disputants ("repeat players") have excessive and unfair structural advantages over individual disputants ("one-shot players")..
The term kangaroo court is often erroneously believed to have its origin from Australia's courts while it was a penal colony. However, the first published instance of the term is from an American source in the year 1853. Some sources suggest that it may have been popularized during the California Gold Rush of 1849, along with mustang court, as a description of the hastily carried-out proceedings used to deal with the issue of claim jumping miners. Ostensibly the term comes from the notion of justice proceeding "by leaps", like a kangaroo – in other words, "jumping over" (intentionally ignoring) evidence that would be in favour of the defendant. Another possibility is that the phrase could refer to the pouch of a kangaroo, meaning the court is in someone's pocket. The phrase is popular in the UK, US, Australia and New Zealand and is still in common use.
The term is sometimes used without any negative connotation. For example, many Major League Baseball and Minor League Baseball teams have a kangaroo court to punish players for errors and other mistakes on the field, as well as for being late for a game or practice, not wearing proper attire to road games, or having a messy locker in the clubhouse. Fines are allotted, and at the end of the year, the money collected is given to charity. The organization may also use the money for a team party at the end of the season.
Some examples of adjudication venues described as kangaroo courts are the People's Court (Volksgerichtshof) of Nazi Germany that convicted people who were suspected of being involved with the failed plot to assassinate Hitler on July 20, 1944.