It must be concluded, therefore, that the tax is not upon the privilege of doing the businesses in which the various corporations in the land are engaged, but is rather a _tax upon the privilege of doing business in a corporate capacity_, or, in other words, upon the exercise of the corporate franchise. That this is so appears very clearly from the message of President Taft. He says: This is an excise tax upon the privilege of doing business as an artificial entity and of freedom from a general partnership liability enjoyed by those who own the stock. Assuming, then, that this is the real nature of the tax, is it constitutional? Unquestionably Congress may tax corporations organized under federal laws upon their franchises; any sovereignty may tax the creatures of its creation for the privilege of exercising their franchises; but how about corporations chartered by the states and doing purely an intrastate business? A state confers on John Doe and his associates the privilege or franchise of doing business in a corporate capacity. Can Congress impose a tax on the exercise of that privilege or franchise? The power to tax involves the power to destroy.[1] If Congress can impose a tax of one per cent., it can impose a tax of ten per cent. or fifty per cent., and thus impair or destroy altogether the value of corporate charters for business purposes. Does Congress possess such a power? The Constitution puts no express limitation on the right of Congress to levy excises except that they shall be "uniform throughout the United States." But there are certain implied limitations inherent in our dual system of government. The sovereignty and independence of the separate states within their spheres are as complete as are the sovereignty and independence of the General Government within its sphere.[2] Neither may interfere with or encroach upon the other. [Footnote 1: _McCulloch vs. Maryland_, 4 Wheat., 316.] [Footnote 2: _The Collector vs. Day_, 11 Wall., 113, 124.]