Originating from Roman law, it was crystallized into a phrase by Edward Coke in the 17th century and is now widely regarded as a fundamental tenet of natural justice and constitutionalism.
[2][3] The Latin brocard nemo judex in causa sua has its origins in the Roman legal tradition and is codified within the Corpus Juris Civilis.
[4] From these Roman sources, the principle has endured into modern times and can be traced in Martin Luther's 1526 work Whether Soldiers, Too, Can Be Saved (Niemand sol sein selbs Richter seyn, meaning "no one should be their own judge"),[5] in Ulrich Zwingli's In Exodum (1527)[6] in Jean Bodin's The Six Books of the Republic (1576)[7] and in Hobbes's Leviathan (1651) ("And seeing every man is presumed to do all things in order to his own benefit, no man is a fit Arbitrator in his own cause").
[4] In the 17th century, the English jurist Edward Coke turned the idea into a phrase when he wrote that "it is a maxim in law aliquis non debet esse iudex in propria causa".
[8] Since then, the rule against bias has been recognised as a fundamental tenet of natural justice in the common law tradition and a cornerstone of constitutionalism.