What Factors Do Courts Consider in Child Custody Decisions?

By Joseph E. Cordell, Co-Founder and Principal Partner, Cordell & Cordell · St. Louis, Missouri | Last reviewed: October 2026

Parents going into a custody case often ask the same question: what will the judge actually look at? The answer is set by state statute, and it is more specific than “the best interests of the child.” Most states give judges a written list of factors, and those lists differ in ways that matter. Missouri now starts from a presumption of roughly equal parenting time. Illinois no longer uses the word “custody” at all.

This guide explains the factors courts commonly weigh, using Missouri and Illinois law as examples, and what kinds of evidence tend to matter under each.

Custody Terms Differ by State

The Best-Interest Factors

Courts decide custody based on the child’s best interests, but statutes define what that means. Missouri’s list in RSMo 452.375 includes the parents’ wishes and proposed parenting plans; the child’s need for a frequent, continuing, and meaningful relationship with both parents; the child’s relationships with parents, siblings, and others; which parent is more likely to allow frequent and meaningful contact with the other; the child’s adjustment to home, school, and community; the mental and physical health of everyone involved, including any history of abuse; any intent to relocate; and the child’s unobstructed input.

Illinois uses a longer list of 17 factors in 750 ILCS 5/602.7, including the amount of caretaking each parent performed in the 24 months before the case was filed, the child’s needs, the distance between the homes and the parents’ ability to cooperate, each parent’s willingness to put the child’s needs first, and any abuse or threats of violence.

No single factor decides most cases, and judges have discretion in how they weigh them. Understanding which factors a state emphasizes helps parents focus on the evidence that will actually be considered.

Who Has Been Doing the Parenting

Past caretaking is one of the most persuasive kinds of evidence, and Illinois writes it directly into its factors. Courts look for a track record, not promises: who has handled school communication, medical appointments, meals, bedtimes, and transportation, and who is available given their work schedule.

• school records and emails with teachers;
• pediatric and dental records showing who attended appointments;
• calendars, messages, and photos showing involvement over time;
• work schedules and the family support available to each parent.

A parent who has not been the primary caregiver is not out of the running. A realistic plan, supported by a schedule and a support network, can carry weight, especially in a state like Missouri that starts from a presumption of shared parenting time.

Stability and the Child’s Adjustment

Both states ask how the child is doing at home, at school, and in the community, and how a proposed arrangement would affect that. Stability does not mean nothing can change; separation already changes the family. The question is whether the plan provides a workable level of consistency in school, housing, and routine. Findattorneys.org’s overview of the effects of divorce on children describes why routine matters at different ages.

Relocation is where stability questions often become disputes. Missouri requires written notice of a proposed move under RSMo 452.377, and Illinois requires notice and, if contested, court approval for qualifying relocations under 750 ILCS 5/609.2. A parent who moves first and asks later can damage their position.

Safety Concerns

Evidence of abuse, neglect, domestic violence, or substance misuse can change the analysis entirely. In Missouri, a finding of a pattern of domestic violence can rebut the equal-parenting-time presumption, and the court must arrange custody to protect the child and the abused parent. In Illinois, a court can restrict a parent’s time when it finds that parent’s exercise of parenting time would seriously endanger the child.

Allegations are not findings. Courts look at police reports, protective orders, medical records, and testimony, and they can appoint a guardian ad litem or order an evaluation when the facts are disputed. False or exaggerated allegations can also affect credibility, and in Missouri, one of the listed factors is which parent is more likely to support the child’s relationship with the other.

The Child’s Preferences

A child’s wishes can matter, but they rarely control the outcome. Illinois considers the child’s wishes in light of maturity and ability to express reasoned and independent preferences. Missouri considers the child’s “unobstructed input,” a phrase that signals courts will discount views that appear coached or pressured. Judges often hear from older children through a guardian ad litem or an interview in chambers rather than testimony in open court.

Whether the Plan Works in Real Life

Both Missouri and Illinois require parenting plans, and judges look closely at whether a proposed schedule fits the family’s actual life: school start times, work shifts, distance between homes, holidays, and how exchanges will happen. Communication matters too. Parents who must share major decisions need to show they can do it without constant conflict.

A history of following, or ignoring, an existing temporary order is often some of the most telling evidence in the case. Parents preparing for a hearing frequently find that legal guidance from the Cordell & Cordell family law attorneys or another family law firm is most useful at this stage, when a plan has to be translated into a schedule a judge will believe both parents can follow.

Which State’s Court Decides

Before any of these factors apply, the right court has to have jurisdiction. Nearly every state has adopted the Uniform Child Custody Jurisdiction and Enforcement Act (UCCJEA), which generally gives initial jurisdiction to the child’s “home state,” where the child lived with a parent for at least six months before the case was filed. Parents who have recently moved should confirm which state’s law will apply before filing.

Frequently Asked Questions

What is the most important factor in a custody case?

There is no single most important factor. Courts weigh all relevant statutory factors, though safety concerns and past caretaking often carry significant weight.

Does Missouri presume 50/50 custody?

Missouri presumes that equal or approximately equal parenting time is in the child’s best interests, but the presumption can be rebutted by evidence, including a pattern of domestic violence.

At what age can a child choose which parent to live with?

Neither Missouri nor Illinois sets an age at which a child decides. Courts consider a child’s wishes based on maturity, along with other factors.

What does Illinois call custody?

Illinois uses “allocation of parental responsibilities,” divided into decision-making responsibilities and parenting time.

Authorities & Sources

1. RSMo 452.375: Missouri custody factors and parenting time presumption
2. RSMo 452.377: Missouri relocation notice
3. 750 ILCS 5/602.5: Illinois decision-making responsibilities
4. 750 ILCS 5/602.7: Illinois parenting time factors
5. 750 ILCS 5/609.2: Illinois parent relocation

Disclaimer

This article provides general information about child custody factors, using Missouri and Illinois law as examples. It is not legal advice, and reading it does not create an attorney-client relationship. Custody laws differ by state and change over time, and every family’s situation depends on its own facts. Parents facing a custody matter should speak with a licensed family law attorney in their state.