De novo is a Latin phrase meaning “anew” or “afresh.” In legal circles it is used to describe a matter or a decision that is to be decided a second time with no regard given to the first decision. For example, in a hearing de novo, a matter is to be decided as if an original decision on the same subject had not been held and as if no decision had been previously rendered.
Often, the term de novo, comes up in the context of an appeal, with respect to what is known as a “standard of review.” If you have lost in front of a court or an administrative board and you appeal the decision, you want a “de novo review,” which means the appeals court or appeal body can start from scratch and reach its own independent decision. Your opponent does not want de novo review, but rather wants some more restrictive standard of review that would result in the appeals court or the appeal body giving a certain degree of deference to the board or the lower court’s decision.
— BBC&B