Invalidating administrative order as "arbitrary, capricious, an abuse of discretion," see 5 U.S.C. § 706, because "[t]he inequity of retroactive policy making . . . is the sort of thing our system of law abhors"
In National Labor Relations Board v. Baltimore T. Co., 4 Cir., 140 F.2d 51, the court alluded with apparent approval to the fact that the Board had endeavored to avoid making its sanctions operate retroactively.