The 16th Amendment did not repeal the apportionment rule of the Constitution. It did not change or amend the Constitution in any way. It did not make legal an unapportioned direct tax on wages or other property. Apportionment was bypassed de facto through the clever mirage of de jure repeal. The 16th only states that Congress may collect an indirect tax on incomes, from whatever ["U.S."] source derived. Congress already had that authority (clearly used in the Corporation Excise Tax Act of 1909), which explains the lack of an enabling clause.

The missing "enabling clause"

Congress has no power but what the States (through the Constitution) give it. Remember, Congress writing a law is one thing; enforcing it is another. Both the law and its enforcement must be authorized in either: 1.) the original Constitution, or 2.) a Constitutional amendment. If Congress seeks to enlarge its current Constitutional authority, then it must go to the States for approval in the form of a Constitutional amendment. Once this new amendment is ratified by three quarters of the States, it is the law of the land and becomes as much a part of the Constitution as the original document as if the Founding Fathers had written it.

If Congress needs new Constitutional authority to enact a new law, then it obviously needs new Constitutional authority to enforce that new law. The two always go hand-in-hand. So, within an amendment, Congress seeks the States' permission for such enforcement in the form of an "enabling clause" (because it enables Congress to enforce its new authority by "appropriate legislation "). Within that amendment are always two components: A) the new law, and B) the enabling clause to enforce that new law. The Union State legislatures must ratify both.

It is important to notice that the 16th Amendment does not have any words or language to allow Congress to 'enforce this article by appropriate legislation.' This is a powerful phrase incorporated in the 13th, 14th, 15th, 18th, and 19th Amendments to enable Congress to legislate for enforcement purposes. Enforcement provisions were not included in the 16th Amendment because no new powers were granted by this Amendment! Article 1, Section 8, Clause 1 of the U.S. Constitution had already granted the necessary [indirect] taxing powers to Congress, J .Eugene Wilson: HOW TO FIGHT THE IRS AND WIN II

When any new Congressional authority is to be granted by an amendment, that amendment must include an enabling clause or Congress is powerless to enforce its new law. Not including such an enabling clause would be like giving somebody a new car-without the keys - the point is this: without an enabling clause, the Congress can't enforce its new law, and what good is a law without powers of enforcement? Good-for-nothing! Surely Congress wouldn't go to the trouble of proposing an allegedly direct tax on income and the repeal of apportionment -without including a simple little enabling clause? (NOTE: Interestingly enough, an enabling clause was not neglected in the 18th Amendment-without which Congress could not have enforced Prohibition, the "War On Booze." Nor did Congress forget enabling clauses in the 19th, 23rd, 24th, and 26th amendments. And as you can see, Congress also knew how to write an enabling clause before the 16th, because it did so in the 13th, 14th, and 15th.