has no power to compel the custodian of the material to risk a contempt citation for his refusal to comply" (internal quotation marks omit- ted)); Overby I. U.S. Fid. & Guar. Co., 224 F.2d 158, 162 & n. 5 (5th Cir.1955) (exercising interlocutory jurisdiction and citing Perlman in a civil action to recover damages for bre