Nunc pro tunc is a Latin expression that translates to “now for then”—meaning to do something now, and for it to have retroactive effect, as if it had been done at a previous time. In the legal context, a judgment nunc pro tunc is a new or changed judgment signed by the court that has retroactive effect to the date the corrected judgment was signed.

The purpose of a judgment nunc pro tunc is to correct a clerical error in the judgment after the court’s authority to change the judgment (its plenary power) has expired. Even a significant change to the original judgment may be accomplished through a judgment nunc pro tunc if it merely corrects a clerical error.

Thus, a judgment nunc pro tunc can generally only be used to correct a clerical error the court made when writing or recording (entering) the judgment the court made (rendered)—and not a judicial error (a substantive error in judicial reasoning) in the judgment. In other words, if the signed judgment inaccurately reflects the true decision of the court, then the error is clerical and may be corrected by judgment nunc pro tunc.

In Arizona, a judgment nunc pro tunc is a legal mechanism used to correct clerical errors in a judgment after the court's authority to amend the judgment has expired. This tool is not intended for substantive changes to the judgment, but rather to ensure that the written record accurately reflects the court's original intent. The correction can be significant, as long as it addresses a clerical mistake rather than a judicial error, which would involve the court's reasoning or decision-making process. The retroactive correction made by a nunc pro tunc order ensures that the judgment is considered to have been entered correctly from the date the original judgment was signed. Arizona courts adhere to this principle under both state statutes and case law, aligning with the general legal practice across the United States.