The most significant constitutional problem in federal taxation today is the absence of constitutional problems. The federal income, estate and gift taxes all encountered an extremely critical reception at the hands of the courts and suffered serious constitutional set-backs early in their careers. Today, however, they function in a constitutional climate as benevolent as it was formerly hostile. A microscopic analysis of the present federal tax system may reveal minor irregularities which might conceivably be magnified into major constitutional issues. From a practical point of view, however, the chance of invalidating a federal tax assessment on constitutional grounds is infinitesimal.
There is no mystery about the radical about-face which has characterized the attitude of the judiciary toward the present federal tax system. Modern federal taxes are more than revenue measures. The federal income, estate and gift taxes represent the aggressive expression of an egalitarian philosophy of sharing the wealth which at first alarmed the courts. The early battles over the constitutionality of the principal federal taxes covertly reflected the more candid struggle which went on in the halls of Congress over the effort of the "have-nots" to shift the bulk of the tax burden to the "haves."'With the defeat of the reactionaries in Congress the scene of the struggle shifted to the courts, where a conservative judiciary strove to throw up constitutional barriers around the status quo.
Charles L.B. Lowndes,
Current Constitutional Problems in Federal Taxation,
4 Vanderbilt Law Review
Available at: https://scholarship.law.vanderbilt.edu/vlr/vol4/iss3/4