Posted on June 15, 2025

Due Diligence In An Illinois Divorce

The law is full of buzzwords that further qualify other legal concepts. One of the most common terms found throughout law in general and family law in particular is “due diligence.”

Due diligence is “[t]he diligence reasonably expected from, and ordinarily exercised by, a person who seeks to satisfy a legal requirement or to discharge an obligation” Black’s Law Dictionary (11th ed. 2019)

The requirement of due diligence is effectively the court system telling litigants to “keep it moving or you’ll lose your rights” which exists in addition to statutes of limitations and other deadlines. Failure to act with due diligence means justice is delayed to the point of denial: evidence goes missing, witnesses forget (or worse, die).

So, while the divorce litigation process feels like a series of delays and continuances, the courts can say “Sorry, it’s been too long. Hurry up and get to it or I’ll cancel your case”

Due Diligence And Service In An Illinois Divorce

Starting a divorce case requires filing a petition for dissolution of marriage and then serving the summons on the opposing side.

“If the plaintiff fails to exercise reasonable diligence to obtain service on a defendant prior to the expiration of the applicable statute of limitations, the action as to that defendant may be dismissed without prejudice.”  Ill. Sup. Ct. R. 103(b)

Service requires due diligence because, as a society, people need to know if they are, in fact, being sued. Otherwise, they’ll just keep doing whatever bad act is being complained of (even if it’s being a bad spouse).

“Due diligence in serving process is essential to this purpose, for it is the sole legally sufficient means of alerting defendants to the pendency of a civil suit. In addition, service with due diligence, by promptly placing defendant on notice of a pending action, shortens the time needed to investigate, prepare and litigate the issues raised, thereby allowing the court to proceed expeditiously to a just resolution of the matter before it. Where a plaintiff (1) fails to exercise due diligence….justice is truly and unnecessarily delayed.”

In reality, due diligence for service is rarely an issue in an Illinois divorce. Illinois divorce courts generate automatic status dates for the court to inquire what is happening in each particular case. Failure to serve the summons should result in the court allowing for service via email, social media or text message.

If service is impossible via personal, substitute, email, social media or text, service by publication is allowed but only after “diligent inquiry [that] his or her place of residence cannot be ascertained” 735 ILCS 5/2-206 (emphasis mine)

Due Diligence In Discovery

The continuances that consume the litigation process are usually the parties requesting, producing and waiting on discovery.

Both parties have a duty to request and answer discovery with due diligence.

Failure to ask for something from the other party or failure to subpoena something from a third party will be seen as a lack of due diligence thus waiving any relief that could have been sought based on that evidence.

“For purposes of pretrial discovery, we take “ordinary” diligence to be synonymous with “due” diligence, and we equate the due diligence requirement in section 2-1401 with the due diligence requirement in section 2-120” In re Marriage of Wolff, 822 NE 2d 596 – Ill: Appellate Court, 2nd Dist. 2005

The court will only allow a second look at discovery if it is determined that the discovery was requested with due diligence.

“In general, to be entitled to relief from judgment, the petitioner must prove…that failure to discover and present the ground for relief was not the result of his own lack of diligence. If his opponent then suppresses information within the scope of the [requested discovery] in such a way as to prevent the inquirer from realizing what has occurred, the failure to discover the information is the result of the former’s fault, not of the latter’s negligence.” Ostendorf v. International Harvester Co., 433 NE 2d 253 – Ill: Supreme Court 1982

This analysis of the requirement for due diligence in discovery is always retroactive when one party is asking for a “do-over” because of the missing discovery. This request to do redo discovery is always in the form of a motion to vacate.

Due Diligence In A Motion To Vacate In An Illinois Divorce

After a court makes a final decision, there are numerous ways to contest that final decision, all of which have timing considerations.

30 days after a final judgment is entered a court can vacate an order for almost any reason it finds just.

“The court may, in its discretion…may on motion filed within 30 days after entry thereof set aside any final order or judgment upon any terms and conditions that shall be reasonable.” 735 ILCS 5/2-1301(e)

After 30 days, the court is going to ask, “what were you waiting on?”

“Relief from final orders and judgments, after 30 days from the entry thereof, may be had upon petition as provided in this Section…All relief…shall be available in every case, by proceedings hereunder, regardless of the nature of the order or judgment from which relief is sought or of the proceedings in which it was entered.” 735 ILCS 5/2-1401

“To be entitled to relief under section 2-1401, the petitioner must affirmatively set forth specific factual allegations supporting each of the following elements: (1) the existence of a meritorious claim or defense; (2) due diligence in presenting that claim or defense in the original action; and (3) due diligence in presenting the section 2-1401 petition.” Cavitt v. Repel, Docket No. 1-13-3382, 13 (Ill. App. Ct. 2015)(emphasis mine)

This is when due diligence matters. A failure to find due diligence in filing the petition to vacate means all the other failures of due diligence that you are trying to correct will be moot.

“No bright-line rule exists for judging whether a petitioner has acted diligently. Rather, due diligence is judged by the reasonableness of the petitioner’s conduct under all of the circumstances. Thus, a six-month delay in requesting section 2–1401 relief does not, ipso facto, demonstrate a fatal lack of diligence.” Paul v. Gerald Adelman & Assocs., Ltd., 223 Ill. 2d 85, 99–100 (2006) (internal citation omitted)

Establishing due diligence requires “reasonable excuse for failing to act within the appropriate time.” Smith v. Airoom, Inc., 499 NE 2d 1381 – Ill: Supreme Court 1986

Typically, the “reasonable excuse” will be that the party wishing to vacate the judgment simply did not know something material that affected their case. After the discovery of that fact, the due diligence clock starts ticking.

In re Marriage of Brubaker, 2022 IL App (2d) 200160, said filing 9-months after the discovery of fraud was sufficient due diligence.

In re Marriage of Sparks, 2018 IL App (1st) 180932, ¶39, found a filing six months after the discovery that a spouse was NOT the father was also sufficient due diligence.

If the motion to vacate is based on fraud the due diligence standard is, effectively, thrown out the window.

“Where there is fraud or unfair conduct, the due diligence requirement will not be strictly enforced.” In re Marriage of Roepenack, 2012 IL App (3d) 110198, ¶40

The due diligence requirement may even be outright ignored where a party has acted unfairly or unconscionably. See Sakun v. Taffer, 268 Ill. App. 3d 343, 354 (1st Dist. 1994).

Even quasi-fraud like misleading testimony or lack of full disclosure relaxes the due diligence requirement.

“In cases involving misleading testimony and lack of full disclosure, principles of equity require relaxing the diligence requirement and vacating the settlement agreement.” In re Marriage of Arjmand, 998 NE 2d 686 – Ill: Appellate Court, 2nd Dist. 2013

Whatever due diligence in filing a petition to vacate is, it’s less than two years.

“[T]he petition [to vacate] must be filed not later than 2 years after the entry of the order or judgment. Time during which the person seeking relief is under legal disability or duress or the ground for relief is fraudulently concealed shall be excluded in computing the period of 2 years.” 735 ILCS 5/2-1401(c)

Lack Of Due Diligence Becomes Waiver

At some point, failure to exercise due diligence becomes waiver.

“Waiver is a voluntary and intentional relinquishment of a known right.” Vaughn v. Speaker, 533 NE 2d 885 – Ill: Supreme Court 1988

If a divorce order is left unenforced. The lack of due diligence in enforcing the order may be interpreted as waiver.

An analysis of whether there was in fact a waiver of contractual provisions focuses on the intent of the nonbreaching party. If he has intentionally relinquished a known right, either expressly or by conduct inconsistent with an intent to enforce that right, he has waived it and may not thereafter seek judicial enforcement.” Whalen v. K Mart Corp., 519 NE 2d 991 – Ill: Appellate Court, 1st Dist. 1988

Failure to exercise due diligence can be considered “conduct inconsistent with an intent to enforce that right” and, therefore, constitute waiver.

Rights that stem from laws rather than contracts typically have an implicit due diligence requirement in that relief will not be granted retroactively.

For married couples, child support and maintenance can only be granted from the date the petition for dissolution of marriage was filed.

“[T]he circuit court [has] the statutory authority to award…maintenance and child support from the date of [the] request in the petition for dissolution, with appropriate credit given for the temporary payments” In re Marriage of Hochstatter, 2020 IL App (3d) 190132

Similarly, college expenses are found to be “in the nature of a modification of child support under section 510. Therefore, [courts shall not order] payment of college expenses that predate the notice of filing as provided in section 510(a)” Petersen v. Petersen, 932 N.E.2d 1184, 1190 (Ill. App. Ct. 2010)

Unmarried parents can ask for child support further back but must consider whether the custodial parent exercised due diligence in informing the other parent of their desire for support.

“The court may order child support payments to be made for a period prior to the commencement of the action. In determining whether and to what extent the payments shall be made for the prior period, the court shall consider all relevant facts, including but not limited to:

The extent to which the mother or the public agency bringing the action previously informed the person obligated to pay support of the child’s needs or attempted to seek or require the help of the person obligated to pay support in raising or supporting the child.” 750 ILCS 46/802(e)(4)

Due diligence need not be only a retroactive analysis. Following a legal process’s steps with due diligence will rewarded with the relief requested. See In re Marriage of Fatkin, 129 NE 3d 1230 – Ill: Supreme Court 2019 where a father’s meticulous relocation package (job offer, schooling, medical care) and presentation helped him win at trial and survive review.

The concept of due diligence really bleeds into everything. Did you do what you were supposed to do on time and under the general principles of common sense? “It is evident both parties have not done their due diligence to facilitate a relationship with the other parent and the children.” In Re Marriage of Stimson, 2018 IL App (4th) 170731-U

If you’re looking to exercise your rights and you want to do so quickly as required by the due diligence standard, contact my Chicago, Illinois family law firm to schedule a free consultation with an experienced Illinois divorce lawyer.

 

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Russell Knight

Russell D. Knight has been practicing family law as a Chicago divorce lawyer since 2006. Russell D. Knight amicably resolves tough cases while remaining a strong advocate for his client’s interests.

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