In regard to the argument that the 16th Amendment changed the rule of apportionment as applied to "direct taxation" keep in mind that to this very day, “direct taxes” are still required to be apportioned as stated by the Court! In Eisner v. Macomber 252 U.S. 189, 206 (1920), a case dealing with direct vs. indirect taxation the tax was struck down as being direct and not apportioned. The Court stated:



“[T]his amendment shall not be extended by loose construction, so as to repeal or modify, except as applied to income, those provisions of the Constitution that require an apportionment according to population for direct taxes....This limitation still has an appropriate and important function, and is not to be overridden by Congress or disregarded by the courts.”



A few years latter in another case dealing with direct vs. indirect taxation, in BROMLEY VS MCCAUGHN, 280 U.S. 124 (1929), the Court emphatically stated “As the present tax is not apportioned, it is forbidden, if direct.”



And let us not forget that even Justice Roberts stated in the Obamacare case:





A tax on going without health insurance does not fall within any recognized category of direct tax. It is not a capitation. Capitations are taxes paid by every person, "without regard to property, profession, or any other circumstance." Hylton, supra, at 175 (opinion of Chase, J.)(emphasis altered). The whole point of the shared responsibility payment is that it is triggered by specific circumstances—earning a certain amount of income but not obtaining health insurance. The payment is also plainly not a tax on the ownership of land or personal property. The shared responsibility payment is thus not a direct tax that must be apportioned among the several
States.



The truth is, the requirement that Representatives and direct taxes are required to be apportioned nas never by changed, nor has Article 1, Section 9, Clause 4 been repealed and declares:

No Capitation, or other direct, Tax shall be laid, unless in Proportion to the Census or Enumeration herein before directed to be taken.

JWK




If, by calling a tax indirect when it is essentially direct, the rule of protection could be frittered away, one of the great landmarks defining the boundary between the nation and the states of which it is composed, would have disappeared, and with it one of the bulwarks of private rights and private property. POLLOCK v. FARMERS' LOAN & TRUST CO., 157U.S. 429 (1895)