Rule 78.01.Granting a New Trial.

Rule 78.01 is the foundation of Missouri's new-trial practice. It gives the trial court broad authority to grant a new trial "upon good cause shown," without listing every specific ground that might qualify. The official comment makes clear that this brevity was a drafting choice, not a substantive cutback — the revision aimed to state the power more concisely, not to eliminate any of the traditional reasons a new trial might be warranted.

The rule also builds in flexibility about scope. A new trial can be granted to all the parties or only some of them, and it can cover all the issues in the case or only part of them. That means a court is not forced into an all-or-nothing choice; it can order a new trial limited to the specific issue or specific party where the problem occurred, leaving the rest of the judgment intact.

For cases tried without a jury, the rule offers an alternative path that does not require a full retrial. On a motion for new trial in a bench-tried case, the court may open a judgment already entered, take additional testimony, amend its findings of fact or make new ones, and then direct entry of a new judgment. This gives a trial judge in a non-jury case a lighter-weight tool to correct or update the outcome without starting over.

Because the rule sets only the framework, the more detailed mechanics that surround it — how many new trials are allowed on a weight-of-the-evidence theory, what an order granting a new trial must say, and how a motion must be framed to preserve error — appear in the rules immediately following, Rule 78.02 through Rule 78.10.