J642 HARVARD LAW REVIEW portation only. Many of the companies included in it may, and im- doubtedly do, have incomes from other sources, such as rents of houses, wharves, stores, and water power, and interest on moneyed investments. ... It is unnecessary, therefore, to discuss the question which would arise if the tax were properly a tax on income. It is clearly not such, but a tax on transportation only." ^ Here obviously Mr. Justice Bradley regards generality as the only essential of a tax "properly a tax on income." He lays no foundation for the distinction between gross and net income reHed on by Mr. Justice Pitney in sustaining the Wisconsin income tax. Nor was it necessary to draw such a distinction in the Oak Creek case, since the generaUty of the tax there involved would have differentiated it from all taxes previously declared invaHd. Had the court been inclined to narrow its decision as much as possible, the opinion might easily have declared that, since the Wisconsin tax was both general and measured by net income, there was no bar against its application to income from interstate commerce, thereby explicitly leaving open for future determination the ques- tion whether either of these qualifications in the absence of the other would entitle the law to the same approval. But, in so far as the opinion rather than the decision is to be looked at as ex- pressing the law for which the case stands, it seems necessary to conclude that a general income tax on gross receipts cannot take toll from interstate commerce. Such gross receipts from interstate as well as local commerce may, as we have seen,^^ be the measure of a tax in lieu of a prop- erty tax, provided the burden thereby imposed is not substantially heavier than what would be laid by the ordinary property tax. If this is true of gross-receipts taxes on selected corporations or enter- prises, it must also be true of a general tax on gross receipts in lieu of a property tax. But such a tax is not likely to be adopted east or west of Russia. One may with safety follow Henry George far enough to disapprove of relieving real estate from ad valorem taxes in order to take only a percentage of the realized gross returns. And though we may anticipate that, in many states, income taxes will soon be substituted for other demands on chattels as well as on intangibles, it is inconceivable that such income taxes will be » 122 U. S. 326, 344-45, 7 Sup. Ct. Rep. 1118 (1887). " 32 Harv. L. Rev. 377-416.
