In 1992 Navistar attempted to reduce its costs for retired employee health and life insurance benefits. Navistar’s retirement benefit plan is a registered employee health benefit plan under the Employee Retirement Income Security Act, 29 U.S.C. § 1001 and Navistar is both plan administrator and fiduciary. In 1993, the district court entered judgment in a class action challenging the change, adopting an agreement between the parties and retaining jurisdiction. The Agreement established the Retiree Health Benefit and Life Insurance Plan. The Plan established the Health Benefit Program Summary Plan Description, which contains a description of the health benefits and is furnished to all beneficiaries. The Agreement divides health benefits into two plans: Plan 2 for those eligible for Medicare and Plan 1 for those who are not eligible. A prescription drug benefit was provided under the Agreement, identical for both Plan 1 and Plan 2. When Navistar moved to substitute Medicare Part D into the Plan, class members claimed violation of the Agreement. The district court ordered Navistar to reinstate, retroactively, the prescription drug benefit that was in effect before Navistar made the unilateral substitution.