by John Marshall Harlan

“ Mobile Gas Service Corp., supra, decided today, we construed the Natural Gas Act as not authorizing unilateral contract changes, and that interpretation is equally applicable to the Federal Power Act. Accordingly, for the reasons there given, we conclude that neither PG&E's filing of the new rate nor the Commission's finding that the new rate was not unlawful was effective to change PG&E's contract with Sierra. ”

“ In short, the Commission holds that the contract rate is unreasonable solely because it yields less than a fair return on the net invested capital. But, while it may be that the Commission may not normally impose upon a public utility a rate which would produce less than a fair return, it does not follow that the public utility may not itself agree by contract to a rate affording less than a fair return or that, if it does so, it is entitled to be relieved of its improvident bargain. ”