Montana Title 25. Civil Procedure § 25-11-102. Grounds for new trial

(1) irregularity in the proceedings of the court, jury, or adverse party or any order of the court or abuse of discretion by which either party was prevented from having a fair trial;

(2) misconduct of the jury. Whenever any one or more of the jurors have been induced to assent to any general or special verdict or to a finding on any question submitted to them by the court by a resort to the determination of chance, the misconduct may be proved by the affidavit of any one of the jurors.

(3) accident or surprise that ordinary prudence could not have guarded against;

(4) newly discovered evidence material for the party making the application that the party could not, with reasonable diligence, have discovered and produced at the trial;

(5) excessive damages appearing to have been given under the influence of passion or prejudice;

(6) insufficiency of the evidence to justify the verdict or other decision or that it is against law;

(7) error in law occurring at the trial and excepted to by the party making the application.