What is the origin of the idiom "kangaroo court" and when to use it?

The exact origin of the idiom "kangaroo court" is uncertain, but it is believed to have emerged in the United States during the mid-19th century. The term draws upon the behavior and reputation of kangaroos, which are known for their hopping and unpredictable movements. It is commonly used to criticize makeshift or informal courts that lack proper legal procedures and impartiality.