INDIRECT ENCROACHMENT ON FEDERAL AUTHORITY 903 the federal system of government, we find the line of demarcation by no means so clear as familiar formulations would entice us to assume. We discover that in certain ways and to a certain extent a state may tax a federal instrumentality and may tax interstate commerce. We face the problem as one of methods and of degree. We see the solution reached by compromise and by practical ad- justment and not by simple discovery of a sharp boundary between two entirely separate spheres of power. We find that the law can- not be summed up in a phrase, but that we must go behind the phrases to the facts. To Chief Justice Marshall we are indebted for clarity and con- fusion on the problem of marking the limits of state power. The confusion appears when he professes clarity, and the clarity is manifest when he owns up to perplexity. By neglecting the con- crete and rising to the heights of pohtical theorizing, Marshall attains an artificial simplicity which would banish all our difficulties, if words alone were adequate to the task. In McCulloch v. Maryland,^ he tells us: "If we measure the power of taxation residing in a State, by the extent of sovereignty which the people of a single State possess, and can confer on its government, we have an intelligible standard applicable to every case to which the power may be applied." ^ Find the limits of state sovereignty, and all difficulties are at an end. Sovereignty is the intelHgible standard applicable to every case. In praise of his solution, Marshall continues: "We have a principle which leaves the power of taxing the people and property of a State unimpaired; which leaves to a State the command of all its resources, and which places beyond its reach, all those powers which are conferred by the people of the United States on the government of the Union, and all those means which are given for the purpose of carrying those powers into execution. We have a principle which is safe for the States, and safe for the Union. We are relieved, as we ought to be, from clashing sovereignty; from interfering powers; from a repugnancy between a right in one government to pull down what there is an acknowl- edged right in another to build up; from the incompatibility of a right in one government to destroy what there is a right in another to pre- serve. We are not driven to the perplexing inquiry, so unfit for the 2 4 Wheat. (U. S.) 316 (1819). ^ Ibid., 429-30.
