Expanding the Nemo Judex Rule: Reflections on Non-Pecuniary Bias

The rule of nemo judex in causa sua (no person ought to judge their own cause) pre-vents a judge or a holder of public office from deciding a matter on which they have a conflicting interest. It is considered ‘one of the twin pillars’ of natural justice across diverse legal traditions. Its judicial use in the UK goes at least as far back as the leading seventeenth-century Bonham case by Sir Edward Coke. In the EU, the maxim has been invariably invoked before the CJEU and lays one of the foundations of the right to an impartial tribunal enshrined in art 47 of the EU’s Charter of Funda- mental Rights. In the US, the Supreme Court has frequently invoked the doctrine and viewed it as a constitutional ‘first principle’.