e record.

[213] 231 U.S. 298 (1913).

[214] 253 U.S. 287, 291, 295 (1920).

[215] 94 U.S. 113 (1877).

[216] 315 U.S. 575, 586.

[217] 320 U.S. 591, 602.--Although this and the previously cited
decision arose out of controversies involving the Natural Gas Act of
1938 (52 Stat. 821), the principles laid down therein are believed to be
applicable to the review of rate orders of State commissions, except
insofar as the latter operate in obedience to laws containing unique
standards or procedures.

[218] 253 U.S. 287 (1920).

[219] In Federal Power Commission _v._ Nat. Gas Pipeline Co., 315 U.S.
575, 599, Justices Black, Douglas, and Murphy, in a concurring opinion,
proposed to travel the road all the way back to Munn _v._ Illinois, and
deprive courts of the power to void rates simply because they deem the
latter to be unreasonable. In a concurring opinion, written earlier in
1939 in Driscoll _v._ Edison Co., 307 U.S. 104, 122, Justice Frankfurter
temporarily adopted a similar position; for therein he declared that
"the only relevant function of law * * * [in rate controversies] is to
secure observance of those procedural safeguards in the exercise of
legislative powers, which are the historic foundations of due process."
However, in his dissent in the Hope Gas Case (320 U.S. 591, 625), he
disassociated himself from this proposal, and asserted that "it was
decided [more than fifty years ago] that the final say under the
Constitution lies with the judiciary."

[220] Federal Power Commission _v._ Hope Gas Co., 320 U.S. 591, 602
(1944).

[221] Federal Power Comm. _v._ Hope Gas Co., 320 U.S. 591, 603 (1944),
citing Chicago & Grand Trunk Ry. Co. _v._ Wellman, 143 U.S. 339, 345-346
(1892); Missouri ex rel. Southwestern Bell Teleph. Co. _v._ Public
Service Commission, 262 U.S. 276, 291 (1923).

[222] For this reason there is presented below a survey of the formulas,
utilization of which was hitherto deemed essential if due process
requirements were to be satisfied.

(1) Fair Value.--On the premise that a utility is entitled to demand a
rate schedule that will yield a "fair return upon the value" of the
property which it employs for public convenience, the Court in 1898, in
Smyth _v._ Ames (169 U.S. 466, 546-547), held that determination of such
value necessitated consideration of at least such factors as "the
original cost of construction, the amount expended in permanent
improvements, the amount and market value o