Another holding of great importance in the Gas case was that the company was entitled to a fair return on the value of real estate used in the business, that value having appreciated very greatly since the original purchase of the real estate, and there being no evidence to show that real estate of so great value was essential to the conduct of the business. The importance of these two holdings is exemplified by the fact that in this particular case the combined value attributed to the franchises and the appreciation of real estate was over $15,000,000--more than one fourth of the total valuation arrived at by the Supreme Court. It will readily be seen that if these two items had been struck from the valuation by the Court, it would be possible for the state to make a still further substantial reduction in the rate charged for gas in New York City without violating the Court's own canon of reasonableness--a six per cent return. The steps in the evolution of the doctrine of judicial review may be summarized in the following manner: The Supreme Court first declared that the legislative determination of what was a "reasonable" rate was not subject to review by the courts. The first departure from this view was an intimation, confirmed with increasing emphasis in several cases, that a rate so low as to make any return whatever impossible was confiscatory and would be set aside by the Court as violating the Fourteenth Amendment. For a time, however, the Court took the position (steadily undermined in subsequent decisions) that a rate which allowed some, even though an "unreasonably low" return, was not prohibited by the Fourteenth Amendment and could not be set aside by the Court. Next in order came the holding that the determination of a commission as to what was reasonable could not be made conclusive upon the courts, at least when the commission had acted without the forms and safeguards of judicial procedure, and, probably, even when it had acted with them. In the same decision appeared an intimation, which in subsequent decisions became crystallized into "settled law," that not only were totally confiscatory rates prohibited by the Fourteenth Amendment, but also any rates which deprived the owners of the property regulated of a return equal to what was "customary" in private enterprises. This rule was applied by the Court for the first time against a rate fixed by a commission, and where the rate was admitted by the pleadings to be confiscatory. But it was shortly thereafter applied to a rate fixed by a legislature, and where the "reasonableness" (not the confiscatory character) of the rate was a direct issue on the facts and evidence.