What is needed to modify a judgment

Unfortunately or in some instanceds perhaps fortunately the parties of a divorce, child custody and/or child support judgment in Missouri, may want to go back to court and argue for a change in the judge’s orders. In legal terminology this is called a modification and it is initiated by filing a motion to modify, typically filed in the same court in which the prior judgment was made. While it is possible to motion the court to make a change, there are certain requirements that must be met for the court to entertain doing so.

                  The requisite criteria for a modification of child custody and a modification of child support are not the same in Missouri.  Missouri Revised Statute section 452.410 details when a modification in child custody can be made. Unfortunately, and perhaps purposefully, the statute is rather vague and lacks specificity. The statute states that a change in custody may be made when “a change has occurred in the circumstances of the child or his custodian and that the modification is necessary to serve the best interests of the child.” However, the allegations of changed circumstances must be based on facts that have materialized since the previous judgment or that were not known to the court at the time of the previous judgment.

Typically, each parent, especially in an adversarial or contentious co-parenting relationship, will have their own ideas of what constitutes the best interests of the child. The ambiguity in the statute does allow a judge very wide discretion as it pertains to making a change in child custody.

  The requisite criteria for a modification of child support is more well defined by the Missouri legislature. Modification of a judgment as to maintenance or child support is governed by Missouri Revised Statute 452.370. The statute states maintenance or [child] support “may be modified only upon a showing of changed circumstances so substantial and continuing as to make the terms unreasonable.” The statute doesn’t stop there, but goes further in detail. The criteria a court will use to determine if a substantial change in circumstances has occurred include:  all financial resources of both parties, including the extent to which the reasonable expenses of either party are, or should be, shared by a spouse or other person with whom he or she cohabits, and the earning capacity of a party who is not employed. The statute gets even more specific with the twenty percent (20%) rule. If the financial circumstances of the parties has changed to the extent that the calculated child support (from Form 14) would differ by more than 20% from the original child support amount ordered in the judgment, a court will assume there has been a change of circumstances so substantial and continuing as to make the present terms unreasonable.

                  A recent case decided by the Eastern District of the Missouri Court of Appeals evaluated an acrimonious case with a long history of back and forth litigation involving child custody. Following an original 2018 order of joint physical and joint legal custody in the case, the mother was able to modify the judgment in her favor for sole legal custody in the June 2024 judgment of modification.

                  Several months later in April of 2025, the father filed another motion to modify claiming the mother’s failure to comply with the modification judgment hurt his ability to father the child. The trial court denied the father’s motion to modify, and the court of appeals affirmed the court’s denial of father’s motion.

The father’s sole evidence in his motion to modify were his complaints about the mother’s exercise of sole legal custody, alleging she would not comply with the parenting plan. The Court of Appeals noted that while a breakdown in communication and cooperation alone can serve as evidence to support a finding of change in circumstances warranting modification of child custody, according to the statute, the circumstances must have been unknown to the court at the time of the prior modification judgment. However in this case, (as mentioned above) the parents had been involved in adversarial litigation since 2018. Indeed, in the 2025 judgment of modification, the court found that the mother’s behavior was in response to the father’s “antagonizing behavior.” The Court denied the father’s motion because mother’s behavior was not new and therefore not a change in circumstances.

                  It’s an important point to remember when attempting to modify a child custody order, that the court will only take into consideration what has happened since the last judgment and the court must have been unaware of any new alleged facts at the time of the previous judgment. This preclusion of relitigating facts and issues that were decided in or prior to the last custody judgment, is known in legalize as “res judicata.”  In latin, res judicata means “a thing adjudicated.”

              The Men’s Center for Domestic Resolution is Kansas City’s fathers’ rights law firm. Attorney Robert Davis is dedicated to helping men through divorce, child custody disputes and other family law matters. You can reach our office in Lone Jack, Missouri at 816-287-1530. We represent men in Jackson, Johnson, Cass, Clay and many of the surrounding counties in western Missouri.