In law, the expression Trial de novo literally means "new trial". It is most often used in certain legal systems that provide for one form of trial, then another if a party remains unsatisfied with the decision.

It is often used in the review of administrative proceedings. If the determination made by a lower body is overturned, it may be renewed de novo in the review process (this is usually before it reaches the court system). Sometimes administrative decisions may be reviewed by the courts on a de novo basis.

One feature that distinguishes an appeal proceeding from a trial de novo is that new evidence may not oridinarily be presented in an appeal, though there are rare instances when it may be allowed usually if it was evidence that only came to light after the trial and could not, in all diligence, have been presented in the lower court. The general rule, however, is that an appeal must be based solely on "points of law", and not on "points of fact". Appeals are frequently based on a claim that the trial judge or jury did not allow or appreciate all the facts; if that claim is successful the appeal judges will often order a trial "de novo". In order to protect the individual's rights against double jeopardy ordering a trial "de novo" is often the exclusive right af an appeal judge.

For example, a system may relegate a claim of a certain amount to a judge but preserve the right to a new trial before a jury.

See also appeal.