Audi alteram partem
Audi alteram partem (or audiatur et altera pars) is a Latin phrase that literally means "It should be heard [audiatur] also the other party", "hear [audi] the other side too", or "hear the alternative party too". It is most often used to refer to the principle that no person should be judged without a fair hearing in which each party is given the opportunity to respond to the evidence against them.
The other principle of natural justice is Nemo iudex in causa sua (or nemo iudex in sua causa) a Latin phrase that means, literally, "no-one should be a judge in their own cause." It is a principle of natural justice that no person can judge a case in which they have an interest. 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".
"Audi alteram partem" is considered a principle of fundamental justice or equity in most legal systems. The principle includes the rights of a party or his lawyers to confront the witnesses against him, to have a fair opportunity to challenge the evidence presented by the other party, to summon one's own witnesses and to present evidence, and to have counsel, if necessary at public expense, in order to make one's case properly.
History of use 
Today, legal systems differ on whether individuals can be convicted in absentia.
The principle is highly used in labour law matters in countries like South Africa and Zimbabwe.
See also 
- audi alteram partem: Definition from the Merriam-Webster Online Dictionary
- Audi alteram partem's entry in the duhaime.org legal dictionary
- e.g. Aeschylus, The Eumenides 431, 435
- Nuclear Tests (Australia c. France), C. I. J., December 20, 1974, p. 265