What is Audi Alteram Partem?

Legal Definition
Audi alteram partem (or audiatur et altera pars) is a Latin phrase meaning "listen to the other side", or "let the other side be heard as well". It is 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.

"Audi alteram partem" is considered to be a principle of fundamental justice or equity or the principle of natural justice in most legal systems. This 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.

The phrase has come to be used as the motto for various political and judicial organisations, and is also the origin of the name of the German carmaker Audi.
-- Wikipedia
Legal Definition
Hear the other side; hear bath sides. No man should be condemned unheard. Broom, Max. 113. See LB-2P.(). 106.
-- Black's Law Dictionary
Legal Definition
Hear the other side. Both sides of a controversy should be heard. See 7 L. R. A. (N. S.) 684.
-- Ballentine's Law Dictionary