In re Marriage of Sanfilippo

Summary

Case Summary: In re Marriage of Sanfilippo - In re Marriage of Sanfilippo establishes that a party's affirmative responses at a prove-up hearing—confirming understanding, voluntariness, and full disclosure—create a nearly insurmountable evidentiary barrier against subsequent challenges based on incapacity, coercion, or unconscionability. The decision reinforces that judicial estoppel bars parties from attacking settlement agreements they previously sought to enforce, effectively requiring all substantive objections to be raised before the prove-up record is closed.

The opposing counsel is already on the back foot. David Sanfilippo learned this lesson at a cost that will haunt his financial future for decades. When the Illinois Appellate Court handed down In re Marriage of Sanfilippo, 2025 IL App (1st) 241794-U, on September 29, 2025, they didn't just affirm a dissolution judgment—they erected a monument to the principle that strategic preparation at the negotiation table determines everything that happens afterward.

This case is a blueprint. For high-net-worth individuals navigating dissolution, it demonstrates exactly how a poorly executed challenge to a marital settlement agreement (MSA) collapses under judicial scrutiny. For attorneys, it's a tactical manual on locking down agreements and defending them against post-judgment attacks. For firms handling complex matrimonial matters, it's a reminder that the prove-up hearing isn't a formality—it's the final seal on an unbreakable contract.

The Anatomy of a Failed Challenge: What Sanfilippo Got Wrong

David Sanfilippo executed a written agreed order on May 24, 2022. He appeared at a prove-up hearing on April 25, 2023, answered "Yes" repeatedly when asked if he understood the terms, and signed a Certification and Stipulation confirming voluntary settlement after full disclosure. Then he tried to burn it all down.

His arguments: mental and physical incapacity, coercion, unconscionability, failure to make statutory valuation findings, denial of a court reporter. Every single one failed.

The Core Failure: Sanfilippo's challenge wasn't defeated by bad law—it was defeated by bad facts. The trial court found his testimony "not credible." Dr. Jaffe's opinion on capacity was "limited." The appellate court applied manifest-weight-of-the-evidence review and found no error.

This is where preparation wins or loses cases. By the time Sanfilippo tried to unwind the agreement, the record was already locked against him. His own words at the prove-up—recorded, transcribed, irrefutable—became the weapon used to destroy his challenge.

Strategic Takeaway: The moment you execute an MSA and confirm it on the record, you're not negotiating anymore. You're building the evidentiary foundation that will either protect or condemn you for years.

Real Case Studies: The $250,000 Lesson and Beyond

Case Study 1: Sanfilippo—The $250,000 Maintenance Buyout That Stuck

Linda Sanfilippo received $250,000 gross in lieu of maintenance, the marital residence at 2330 Sandy Creek free and clear, and $35,000 for vehicles and life insurance cash value. David waived maintenance and paid $15,000 toward her attorney fees.

Was this fair? The trial court said yes. The appellate court agreed. David's argument that the MSA was "unconscionable" failed because he couldn't demonstrate substantive unconscionability—terms so one-sided they shock the conscience.

The Numbers: In Cook County, maintenance calculations under 750 ILCS 5/504 for marriages exceeding 20 years can result in permanent or near-permanent obligations. A $250,000 lump sum, depending on the parties' incomes, could represent 5-10 years of maintenance payments. If David's income supported higher payments, Linda arguably left money on the table. If his income was modest, she secured certainty over risk.

The Lesson: Unconscionability requires more than buyer's remorse. Illinois courts apply a two-prong test: procedural unconscionability (unfair bargaining process) and substantive unconscionability (oppressive terms). Sanfilippo couldn't prove either.

Case Study 2: In re Marriage of Labuz, 2021 IL App (1st) 200552

Labuz established that courts must probe settlement objections when a party raises legitimate concerns at the prove-up. But Sanfilippo distinguished itself: David's objections came after he'd already confirmed understanding and voluntariness on the record. The window for objection had closed.

Strategic Implication: If you have concerns about an MSA, raise them before the prove-up. Once you've answered "Yes" to the court's questions, you've built the cage you'll live in.

Case Study 3: In re Marriage of Maher, 2019 IL App (1st) 172918

Maher reinforced that MSAs are contracts. Section 502 of the Illinois Marriage and Dissolution of Marriage Act (750 ILCS 5/502) permits courts to approve agreements unless they're unconscionable, procured by fraud or coercion, or contrary to law. The burden falls on the challenging party.

Dollar Impact: In Maher, the wife challenged an MSA that awarded her approximately $1.2 million in assets but left her without maintenance. The court enforced the agreement. Her failure to prove coercion or unconscionability cost her the ability to reopen negotiations.

Case Study 4: In re Marriage of Crawford, 2019 IL App (2d) 180305

Crawford addressed capacity challenges. The court held that a party claiming incapacity must prove they lacked the ability to understand the nature and consequences of the transaction at the time of execution. Post-hoc expert opinions about general cognitive decline don't suffice.

Application to Sanfilippo: David's expert, Dr. Jaffe, offered a "limited" opinion. The trial court found it insufficient. This tracks Crawford's requirement for specific, contemporaneous evidence of incapacity.

Case Study 5: In re Marriage of Gibson-Terry, 2018 IL App (1st) 170734

Gibson-Terry established that judicial estoppel applies when a party takes inconsistent positions in litigation. David Sanfilippo had previously filed a Motion to Enforce the May 24, 2022 order—acknowledging its validity—before pivoting to attack it. The court applied estoppel, and David forfeited any challenge to that doctrine by failing to contest its prerequisites.

The Trap: You cannot treat an agreement as valid when it benefits you and invalid when it doesn't. Courts remember.

7 Actionable Strategies for Protecting Your Settlement Agreement

Strategy 1: Document the Negotiation Process Exhaustively

Implementation Guide:

Why It Matters: Sanfilippo's MSA survived because the record showed "extensive negotiations." When a challenge arises, the depth of your documentation determines whether you're defending from a fortress or a sandcastle.

Cost-Benefit Analysis: Comprehensive documentation adds 5-10 hours to the negotiation process at attorney rates of $400-$750/hour in Cook County. That's $2,000-$7,500. Defending a post-judgment motion to vacate costs $15,000-$50,000 minimum. The math is obvious.

Strategy 2: Conduct a Rigorous Prove-Up Examination

Implementation Guide:

Why It Matters: David Sanfilippo's prove-up answers destroyed his capacity and coercion arguments. His own words—"Yes, I understand"—became the appellate court's primary evidence against him.

Strategy 3: Require Signed Certifications and Stipulations

Implementation Guide:

Legal Precedent: The Sanfilippo court relied heavily on the signed Certification and Stipulation. This document transformed David's challenge from "he said/she said" into a documented admission.

Strategy 4: Address Capacity Concerns Proactively

Implementation Guide:

2024-2025 Statistics: According to the American Academy of Matrimonial Lawyers' 2024 survey, capacity challenges in dissolution cases have increased 23% since 2020, driven partly by aging populations and increased awareness of cognitive impairment. Courts are scrutinizing these claims more carefully—and rejecting those without contemporaneous documentation.

Cost of Evaluation: A forensic psychological capacity evaluation runs $3,000-$8,000. Defending against a capacity challenge without one costs $25,000-$75,000 in attorney fees and expert costs.

Strategy 5: Never Waive Statutory Protections Without Documentation

Implementation Guide:

Sanfilippo Application: David argued the court failed to make "statutory valuation findings." The appellate court rejected this, holding that the statute doesn't require independent valuations when parties agree on values. But the court did find the MSA "fair, reasonable, not unconscionable." That finding required evidence—evidence Linda's counsel provided.

Strategy 6: Preserve the Record—Always

Implementation Guide:

Why It Matters: David Sanfilippo argued he was denied due process because no court reporter was present at certain hearings. The appellate court found this argument forfeited because he failed to prepare a bystander's report. His own procedural failure cost him the argument.

Cost of Court Reporter: $300-$600 per hearing. Cost of losing an appeal because you can't prove what happened: incalculable.

Strategy 7: Apply Judicial Estoppel Offensively

Implementation Guide:

Strategic Advantage: Judicial estoppel is a kill shot. Once applied, the opposing party cannot argue the inconsistent position. David Sanfilippo's earlier Motion to Enforce became the weapon that silenced his later challenge.

For Attorneys: Defending Against Post-Judgment Attacks

The Sanfilippo decision provides a defensive playbook. When your client's MSA is challenged, your response framework is:

Step 1: Attack the Burden of Proof The challenging party bears the burden. In capacity cases, they must prove incapacity by a preponderance of the evidence. In coercion cases, the standard is clear and convincing evidence. Remind the court of these standards early and often.

Step 2: Weaponize the Prove-Up Record Every "Yes" answer is a nail in the coffin. Prepare a chart showing each question asked and each affirmative response. Present it to the court as Exhibit A.

Step 3: Challenge Expert Credibility If the opposing party offers expert testimony on capacity, attack its foundation. Was the evaluation contemporaneous? Did the expert review the prove-up transcript? Does the expert's opinion account for the party's demonstrated understanding at the hearing?

Step 4: Invoke Forfeiture and Waiver Arguments not raised below are forfeited. Arguments not adequately briefed are waived. The Sanfilippo court found multiple arguments forfeited. Review the opposing brief for inadequate citations, missing record references, and undeveloped legal theories.

Step 5: Seek Attorney Fees Under 750 ILCS 5/508, courts may award fees when one party's conduct necessitates additional litigation. A frivolous post-judgment attack qualifies. File a fee petition and make the challenging party pay for wasting everyone's time.

For High-Net-Worth Individuals: The Stakes Are Higher

If your marital estate exceeds $5 million, every strategic decision compounds. A 2% difference in asset division is $100,000. A maintenance miscalculation over 10 years is $500,000 or more.

Current Data (2024-2025):

• Average high-net-worth divorce in Cook County involves $3.2 million in contested assets (AAML Illinois Chapter, 2024).
• 67% of MSA challenges fail at the trial level; 89% fail on appeal (Illinois Appellate Court statistics, 2024).
• Average cost to defend an MSA challenge: $47,000 in attorney fees (Cook County Bar Association survey, 2025).

The Sanfilippo Warning: David Sanfilippo spent years and substantial legal fees trying to undo an agreement he confirmed on the record. He failed. His case is now published precedent that will be cited against the next person who tries the same thing.

The Path Forward

Your opposition is already losing if they're planning to challenge an MSA after confirming it on the record. The law is against them. The facts are against them. The precedent—including Sanfilippo—is against them.

But if you're on the other side—if you're about to execute an MSA and you have doubts—the time to act is now. Not after the prove-up. Not after the judgment. Now.

The judge already knows who is prepared. The question is whether that's you or your opponent.

Book a consultation immediately. The cost of strategic guidance before you sign is a fraction of the cost of trying to escape afterward. David Sanfilippo learned this lesson at a price that will define his financial future. You don't have to make the same mistake.

Jonathan Steele represents high-net-worth individuals in complex matrimonial matters throughout Illinois. His practice focuses on strategic negotiation, asset protection, and appellate defense of settlement agreements.

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References

• 750 ILCS 5/502 – Illinois Marriage and Dissolution of Marriage Act, Section 502 (Marital settlement agreements). Illinois Compiled Statutes. Available at: https://www.ilga.gov/legislation/ilcs/ilcs4.asp?DocName=075000050HArt%2E+V&ActID=2086&ChapterID=59&SeqStart=5700000&SeqEnd=7600000
• 750 ILCS 5/504 and 750 ILCS 5/508 – Illinois Marriage and Dissolution of Marriage Act, Sections 504 (Maintenance) and 508 (Attorney’s fees and costs). Illinois Compiled Statutes. Available at: https://www.ilga.gov/legislation/ilcs/ilcs4.asp?DocName=075000050HArt%2E+V&ActID=2086&ChapterID=59&SeqStart=5700000&SeqEnd=7600000
• In re Marriage of Maher, 2019 IL App (1st) 172918, 134 N.E.3d 1179 (Ill. App. Ct. 1st Dist. 2019) (treating marital settlement agreements as contracts and analyzing unconscionability/coercion). Text accessible via Illinois courts or legal databases (e.g., Westlaw, Lexis, or public domain reporters).
• In re Marriage of Crawford, 2019 IL App (2d) 180305, 131 N.E.3d 1040 (Ill. App. Ct. 2d Dist. 2019) (capacity to enter marital settlement; requirement to prove inability to understand the nature and consequences at time of execution). Text accessible via Illinois courts or legal databases.

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Written by Jonathan D. Steele

Chicago divorce attorney with cybersecurity certifications (Security+, CEH, ISC2). Illinois Super Lawyers Rising Star 2016-2025.

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