In re Marriage of Gill, 2025 IL App (5th) 240890-U

The opposing counsel is already on the back foot—they just don't know it yet. In In re Marriage of Gill, the Fifth District Appellate Court handed down a ruling that should make every family law practitioner in Illinois sit up and take notice. The trial court got reversed. Hard. And the reason? A fundamental misunderstanding of the statutory framework that governs parental decision-making modifications versus parenting time modifications.

If you're litigating custody disputes in Cook County or anywhere in Illinois, this case is your new playbook. If you're on the receiving end of a modification motion filed by opposing counsel who doesn't understand the difference between these two standards, you now have a loaded weapon in your arsenal.

The Critical Distinction Your Opposition Keeps Missing

Here's what the trial court in Gill got wrong—and what too many practitioners continue to bungle: (a) creates two entirely separate legal frameworks for modifying custody arrangements. Conflate them at your peril.

Parental Decision-Making Modifications: The Two-Year Bar

Motions to modify the allocation of parental decision-making responsibilities are barred for two years after entry of the original order. Full stop. The only exception? The court may permit an earlier motion if the moving party files affidavits demonstrating reason to believe the child's present environment:

• Seriously endangers the child's mental, moral, or physical health, OR
• Significantly impairs the child's emotional development

This isn't a "best interests" analysis. This is a threshold gatekeeping function. You don't get to argue about what's best for the child until you've cleared the serious-endangerment hurdle. The trial court in Gill skipped straight to best interests without addressing whether the statutory prerequisites had been met. The appellate court called it what it was: an abuse of discretion.

Parenting Time Modifications: Different Standard, Different Timing

Parenting time modifications operate under an entirely separate framework. There's no two-year bar. You can file at any time. But you must demonstrate:

1. Changed circumstances that necessitate modification, AND
2. That the modification serves the child's best interests

The appellate court in Gill emphasized that these analyses must be conducted separately. The trial court's failure to do so—its conflation of the two standards—warranted reversal and remand.

Strategic Applications: Offense and Defense

If You're Filing the Modification Motion

Before you draft that petition, ask yourself: Am I seeking to modify decision-making responsibilities, parenting time, or both?

If decision-making within two years of the original order:

• Your motion must include supporting affidavits alleging serious endangerment or significant impairment of emotional development
• Generic allegations won't cut it—be specific, be documented, be prepared to prove it
• If you can't meet this threshold, wait until the two-year period expires

If parenting time:

• Lead with changed circumstances—what's different now from when the original order was entered?
• Connect those changes directly to the child's best interests
• Don't rely on a generic "best interests" argument without establishing the predicate changed circumstances

If You're Defending Against the Motion

This is where Gill becomes your tactical advantage. When opposing counsel files a modification motion within two years that seeks to change decision-making responsibilities:

• Immediately scrutinize whether the required affidavits have been filed
• If the affidavits are missing or insufficient, file a motion to dismiss or strike
• If the trial court attempts to proceed on a "best interests" analysis without first addressing the serious-endangerment threshold, object on the record and preserve the issue for appeal

The appellate court in Gill made clear that failure to follow the statutory framework is reversible error. Your opposition may win at the trial level through judicial error, but you'll own them on appeal.

The Digital Evidence Angle Your Opposition Isn't Considering

In high-net-worth custody disputes, the serious-endangerment threshold often intersects with digital evidence. Consider the scenarios where a parent's online conduct, cybersecurity failures, or digital communications become relevant:

• A parent's social media activity exposing the child to inappropriate content or dangerous individuals
• Failure to secure devices that the child uses, resulting in exposure to harmful material
• Digital communications revealing substance abuse, domestic violence, or other endangering conduct
• Parental alienation documented through text messages, emails, or recorded communications

If you're building a serious-endangerment case, your discovery requests should target digital evidence aggressively. Forensic analysis of devices, social media preservation demands, and subpoenas to platform providers can yield the documentation you need to clear the statutory threshold.

Conversely, if you're defending against such a motion, conduct a thorough audit of your client's digital footprint before opposing counsel does. What's on those devices? What's in those cloud accounts? What have they posted, messaged, or searched? You need to know before the other side does.

Trial Court Requirements: What Gill Demands

The appellate court's guidance to trial courts is explicit: analyze and state findings separately for the serious-endangerment threshold and the changed circumstances/best interests analysis.

This means:

• If decision-making modification is sought within two years, the court must first determine whether the affidavits establish grounds to proceed
• Only after clearing that threshold may the court conduct a best interests analysis
• For parenting time modifications, the court must make specific findings regarding changed circumstances before applying the best interests factors
• A generic "best interests" ruling that fails to address these predicate requirements is vulnerable to reversal

As an advocate, your job is to force the court to follow this framework. Structure your arguments accordingly. File proposed findings of fact that track the statutory requirements. Make the court's job easier—and create a clear appellate record if the court deviates.

Procedural Traps: The Amended Pleading Gambit

One detail from Gill that deserves attention: the appellate court noted concerns about amended pleadings filed close to trial. If opposing counsel attempts to pivot their theory of the case through late amendments—particularly amendments that attempt to invoke the serious-endangerment exception without proper affidavit support—object immediately and preserve the record.

Trial courts have discretion to permit amendments, but that discretion isn't unlimited. An amendment that fundamentally changes the legal basis for relief, filed on the eve of trial, can be challenged as prejudicial. Don't let opposing counsel sandbag you with a last-minute theory shift.

The Bottom Line

In re Marriage of Gill is a masterclass in what happens when practitioners and courts fail to respect the statutory framework. The trial court applied the wrong standard. The appellate court reversed. The case gets relitigated. Everyone loses time and money—except the lawyers billing for the appeal.

Don't be the practitioner who makes this mistake. Don't be the client whose case gets reversed because your attorney didn't understand the distinction between decision-making and parenting time modifications.

The statute is clear. The appellate court has now underscored that clarity. There's no excuse for getting this wrong.

If you're facing a custody modification dispute in Illinois—whether you're seeking to modify an existing order or defending against a motion that doesn't meet the statutory requirements—you need counsel who understands these distinctions at a granular level.

Book a strategy session now. Your opposition is already making mistakes. Let's make sure you capitalize on every single one.