M & K Employee Solutions, Inc. v. Trustees of IAM Nat. Pension

Summary

The Court held that ERISA §§ 1391 and 1393 do not require actuarial assumptions used to calculate withdrawal liability to be selected on or before the measurement date, affirming the D.C. Circuit’s judgment. The decision resolves a split with the Second Circuit and rejects petitioners’ arguments based on statutory text, antiretrospective provisions, and policy concerns.