In Martin v. District of Columbia22 was involved a law of Congress relating to the District of Columbia providing for the opening of alleys and the assessment of damages upon the lots in the squares concerned. Contest was made by certain lot owners that their properties would not be benefited, at least to the extent of the assessments, by the opening of alleys. The court, after referring to the terms of the law, say;

"The law is not a legislative adjudication concerning a particular place and a particular plan, like the one before the court in Wight v. Davidson, 181 U. S. 371; 21 Sup. Ct. Rep. 616; 45 L. ed. 900. It is a general prospective law. The charges in all cases are to be apportioned within the limited taxing district of a square, and therefore it well may happen, it is argued, that they exceed the benefit conferred, in some case of which Congress never thought and upon which it could not have passed. The present is said to be a flagrant instance of that sort. If this be true, perhaps the objection to the act would not be disposed of by the decision in Louisville & N. R. Co. v. Barber Asphalt Paving Co., 197 U. S. 430; 25 Sup. Ct Rep. 466; 49 L. ed. 819. That case dealt with the same objection, to be sure, in point of form, but a very different one in point of substance. The assessment in question there was an assessment for grading and paving, and it was pointed out that a legislature would be warranted in assuming that grading and paving streets in a good-sized city commonly would benefit adjoining land more than it would cost. The chance of the cost being greater than the benefit is slight, and the excess, if any, would be small. These and other considerations were thought to outweigh a merely logical and mathematical possibility on the other side, and to warrant sustaining an old and familiar method of taxation. It was emphasized that there should not be extracted from the very general Language of the 14th Amendment, a system of delusive exactness and merely logical form.

"But when the chance of the cost exceeding the benefit grows large, and the amount of the not improbable excess is great, it may not follow that the case last cited will be a precedent. Constitutional rights like others are matters of degree. To illustrate: Under the police power, in its strict sense, a certain limit might be set to the height of buildings without compensation; but to make that limit five feet would require compensation and a taking by eminent domain. So it well might be that a form of assessment that would be valid for paving would not be valid for the more serious expenses involved in the taking of land. Such a distinction was relied on in French v. Barber Asphalt Paving Co. (181 U. S. 324; 21 Sup. Ct. Rep. 625; 45 L. ed. 879) to reconcile the decision in that case with Norwood v. Baker (172 U. S. 269; 19 Sup. Ct. Rep. 187; 43 L. ed. 443)."

22 205 U. S. 135; 27 Sup. Ct Rep. 440; 51 L. ed. 743.

But it is evident that the court itself felt that a position was being taken which could not be clearly harmonized with earlier cases, for the opinion continues:

"And yet it is evident that the act of Congress under consideration is very like earlier acts that have been sustained. That passed upon in Wight v. Davidson, it is true, dealt with a special tract, and so required the hypothesis of a legislative determination as to the amount of benefit conferred. But the real ground of the decision is shown by the citation of Bauman v. Ross (167 U. S. 548; 17 Sup. Ct. Rep. 966; 42 L. ed. 270), when the same principle was sustained in a general law. It is true again that in Bauman v. Ross the land benefited was to be ascertained by the jury instead of being limited by the statute to a square; but it was none the less possible that the sum charged might exceed the gain. As only half the cost was charged in that case it may be that, on the practical distinction to which we have adverted in connection with Louisville & N. R. Co. v. Barber Asphalt Paving Co. the danger of such an excess was so little that it might be neglected, but the decision was not put on that ground.

"In view of the decisions to which we have referred it would be unfortunate if the present act should be declared unconstitutional after it has stood so long. We think that without a violent construction of the statute it may be read in such a way as not to raise the difficult question with which we have been concerned. It is true that the jury is to apportion an amount equal to the Constitutional Limitations Upon Taxing Powers. 943 amount of the damage ascertained, but it is to apportion it 'according as each lot or part of lot of land in such square may be benefited by the opening, etc.'Very likely it was thought in general, having regard to the shortness of the alleys, the benefits would be greater than the cost. But the words quoted permit, if they do not require, the interpretation that in any event the apportionment is to be limited to the benefit, and if it is so limited all serious doubt as to the validity of the statute disappears."