Definition & Meaning of "judge, jury, and executioner"

What is the origin of the idiom "judge, jury, and executioner" and when to use it?

The idiom "judge, jury, and executioner" has its origins in the concept of frontier justice, particularly during the American Old West era. In those times, when law enforcement was often limited or absent, individuals or groups would take it upon themselves to maintain order and administer justice. This involved assuming the roles of judge, jury, and executioner, making decisions on guilt or innocence and carrying out punishments without formal legal proceedings. This phrase is commonly used in discussions surrounding issues of justice, governance, and authority, particularly when there are concerns about abuse of power, lack of accountability, or the absence of impartiality.