Lawyers for University of Pennsylvania employees and retirees suing the school for alleged retirement-benefits violations asked the U.S. Supreme Court on Wednesday to turn down a petition that said the allegations had failed to meet certain threshold standards to proceed in court.

Participants in Penn’s $3.8 billion retirement plan won a key ruling in the U.S. Court of Appeals for the Third Circuit last year that revived core elements of the complaint alleging a breach of fiduciary duty under the federal Employee Retirement Income Security Act, or ERISA. The plan participants, represented by Jerome Schlichter of the St. Louis firm Schlichter Bogard & Denton, contend Penn “caused the plan to pay wholly unnecessary fees, resulting in millions of dollars in lost retirement savings.”