pass on the “equity of restitution” in addition to the reasonableness of past rates, and in that case denied all recovery largely because of the absence of a fund of net unjust enrichment and lack of carrier willfulness in charging the unlawful fares); Niagara Mohawk Power Co. v. FPC, 126 U.S.App.D.C. 376, 380-83, 379 F.2d 153, 157-60 (1967) (agency has authority to assign effective date earlier than date of the issuance of the license, when project was maintained without license in violation of applicable law, in a discriminating manner that takes into account the willfulness of past noncompliance). 76 . Equitable factors may bar all retroactive relief. See, e. g., Buckley v. Valeo, 424 U.S. 1, 142, 96 S.Ct. 612, 693, 46 L.Ed.2d 659, 758, 44 U.S.L.W. 4127, 4170 (U.S. Jan. 30, 1976) (<HOLDING>); Blair v. Freeman, 125 U.S.App.D.C. 207, 218,
recognizing de facto validity of past action of improperly constituted election commission and granting stay for 30 days  subsequently extended another 20 days  to permit it to function in the interim and allow congress time to reconstitute the commission in conformance with the constitution holding that a difference between 384 days prepreference average number of days to payment and 547 days preference average number of days to payment did not make the payments out of the ordinary course of business holding that a difference between approximately 54 days prepreference average days to payment and approximately 67 days preference average days to payment did not make the payments out of the ordinary course of business holding that 120 days notice was satisfied by 30 days work plus 90 days pay holding that the language of the statute is mandatory and the commission must act within 180 days