Nemo iudex in causa sua
Nemo judex in causa sua (or nemo judex in sua causa) is a Latin phrase that means, literally, "no-one is judge in his own cause." It is a principle of natural justice that no person can judge a case in which they have an interest. In many jurisdictions the rule is very strictly applied to any appearance of a possible bias, even if there is actually none: "Justice must not only be done, but must be seen to be done".
This principle may also be called:
- nemo judex idoneus in propria causa est
- nemo judex in parte sua
- nemo judex in re sua
- nemo debet esse judex in propria causa
- in propria causa nemo judex
The legal effect of a breach of natural justice is normally to stop the proceedings and render any judgment invalid; it should be quashed or appealed, but may be remitted for a valid re-hearing.
- "Legal definition of Nemo judex in causa sua". legal-glossary.org. 23 March 2013. Retrieved 24 February 2014.
- R v Sussex Justices, ex parte McCarthy,  1 KB 256,  All ER 233
- ABA Journal, "Show Me the Money: States, ABA Try to Figure Out When Campaign Cash Leads to a Judge’s Recusal", 1 March 2012 (retrieved 28 June 2017).
- Zwingli, Ulrich (1544). "Operum: Ea, Quae in Genesim, Exodum, Esaiam & Ieremiam prophetas, partim ex ore illius excepta, partim ab illo conscripta sunt, una cum Psalterio Latinitate donato, co[n]tinens. Tomus Tertius".