In re Marriage of Mueller, 2015 IL 117876

1. Case citation and parties
- In re Marriage of Mueller, 2015 IL 117876 (Ill. S. Ct. June 18, 2015).
- Shelley L. Mueller (appellee) v. Christopher Mueller (appellant).

2. Key legal issues
- Whether a state court must reduce a non‑participant spouse’s government pension by the value of hypothetical Social Security benefits he cannot receive (i.e., an “in lieu of” or WEP/GPO adjustment) so as to put him in a position similar to the other spouse who receives Social Security, when federal law (42 U.S.C. § 407) bars attachment/assignment of Social Security benefits.
- Whether expert testimony using that valuation methodology is admissible.

3. Holding/outcome
- Illinois Supreme Court affirmed the trial and appellate courts: the trial court properly excluded the valuation adjustment and expert testimony based on it; the pension should not be reduced by a hypothetical Social Security offset. Case remanded consistent with decision.

4. Significant legal reasoning (concise)
- The Dissolution Act requires division of marital property (750 ILCS 5/503), and pensions are marital property. But federal law broadly protects Social Security benefits from assignment/attachment (42 U.S.C. § 407(a)).
- In In re Marriage of Crook, this Court already held Social Security benefits cannot be used as a divisible asset or as a basis for offset in state dissolution proceedings. Mueller squarely applied Crook: even a valuation that does not directly divide the former spouse’s Social Security but reduces the other spouse’s pension by the value of hypothetical Social Security benefits would “cause an actual difference in the asset distribution” and is therefore prohibited.
- The court rejected reliance on out‑of‑state decisions (e.g., Oregon’s Herald) that permit such offsets, concluding Crook controls and federal protections preempt valuation methods that effectively reach Social Security benefits. Standard of review: de novo.

5. Practice implications for family law attorneys (practical points)
- In Illinois, do not attempt to value a non‑participant public pension by subtracting hypothetical Social Security benefits (WEP/GPO) as an “in lieu of” adjustment; such methodology risks exclusion and reversal under Crook/Mueller.
- To address inequity caused by one spouse lacking Social Security coverage, craft settlements using divisible assets (cash, other retirement accounts, maintenance, property) rather than pension offsets tied to Social Security.
- Prepare alternative valuation methods for pensions and be ready to argue equitable distribution under 503(d) factors; if offering expert testimony, avoid calculations that seek to monetize or offset Social Security entitlements.
- Consider legislative remedies or stipulations in settlements if parties want to approximate parity between pensioned public‑sector employees and Social Security participants.