Represented Marathon Oil Company in its appeal of the district court's decision that its plan administrator abused its discretion by defining the term "children" in an ERISA-governed plan to mean biological and legally-adopted children. A deceased plan participant's stepchildren, who had been denied the proceeds of his plan account by the plan administrator, argued that the plan administrator should have considered the state law doctrine of equitable adoption to determine that they were "children" and therefore entitled to the deceased's benefits. The Fifth Circuit issued an opinion reversing the district court's decision, finding that nothing in the plan or ERISA required the plan administrator to incorporate the doctrine of equitable adoption into the plan's definition of "children."