The Federal Rules of Civil Procedure
New Trial; Altering or Amending a Judgment
(a) In General.
(1) Grounds for New Trial. The court may, on motion, grant a new trial on all or some of the issues—and to any party—as follows:
(A) after a jury trial, for any reason for which a new trial has heretofore been granted in an action at law in federal court; or
(B) after a nonjury trial, for any reason for which a rehearing has heretofore been granted in a suit in equity in federal court.
(2) Further Action After a Nonjury Trial. After a nonjury trial, the court may, on motion for a new trial, open the judgment if one has been entered, take additional testimony, amend findings of fact and conclusions of law or make new ones, and direct the entry of a new judgment.
(b) Time to File a Motion for a New Trial. A motion for a new trial must be filed no later than 28 days after the entry of judgment.
(c) Time to Serve Affidavits. When a motion for a new trial is based on affidavits, they must be filed with the motion. The opposing party has 14 days after being served to file opposing affidavits. The court may permit reply affidavits.
(d) New Trial on the Court's Initiative or for Reasons Not in the Motion. No later than 28 days after the entry of judgment, the court, on its own, may order a new trial for any reason that would justify granting one on a party's motion. After giving the parties notice and an opportunity to be heard, the court may grant a timely motion for a new trial for a reason not stated in the motion. In either event, the court must specify the reasons in its order.
(e) Motion to Alter or Amend a Judgment. A motion to alter or amend a judgment must be filed no later than 28 days after the entry of the judgment.