Now, just like all sorts of deductions from taxable income, a new deduction is added – one that allows a person to deduct the cost of health insurance if it meets certain criteria. I doubt seriously anyone would claim deductions could be Unconstitutional. I've never seen anyone try to make such an argument, but maybe they have.

Does anyone think the mortgage interest deduction is Unconstitutional? How about the standard deduction or the personal exemptions for dependent children? Are those Unconstitutional? I don't think so. I think the government is perfectly within its authority to allow any deduction it wants – except ones based on race, religion, etc.

So, here we have a tax to pay the debt, or to fund the military, or to pay costs associated with anything the government is empowered to do. Then, we have a deduction that can be itemized. That's all that is required. It's simple, and it's Constitutional. I haven't seen a persuasive argument to the contrary.

I am not condoning such a practice. I'm just laying it out there.

Can Congress Constitutionally set tax rates at 50%, 70% or more? Yes. Undoubtedly.

Can Congress carve out all sorts of deductions to arrive at "taxable" income? Yes. Undoubtedly.

Madison is irrelevant. The income tax was implemented well after he was gone.

"The powers delegated by the proposed Constitution to the federal government, are few and defined. Those which are to remain in the State governments are numerous and indefinite. The former will be exercised principally on external objects, as war, peace, negotiation, and foreign commerce; with which last the power of taxation will, for the most part, be connected. The powers reserved to the several States will extend to all the objects which, in the ordinary course of affairs, concern the lives, liberties, and properties of the people, and the internal order, improvement, and prosperity of the State."

and health care does not fall under the umbrella of federal power as explained by Madison, then arguing the application and scope of the taxing power, the Commerce Clause or the Necessary and Proper Clause relative to health care is nothing but an argument over the degree of a usurpation of power.

The federal government does not have the constitutional authority to invoke the delegated powers to do things that were never entrusted to that government in the first place.

In my mind that is the real argument!

The mortgage interest deduction encourages home ownership. Your effective rate will be higher if you do not finance the purchase of a home.

So, would it be Constitutional for Congress to impose a 15% tax increase across the board and then, turn around and give generous deductions to those who purchase health insurance meeting certain requirements? I think so. We've seen ample case law both ways on whether the tax power (specifically, imposition of a tax) can be used when it "happens" to change/regulate behavior (thus, indirectly regulating matters beyond the commerce power). However, I'd be surprised if any court would ever hold that a general tax rate across the board, coupled with a specific deduction, would violate the commerce clause.

There really are just too many ways to skin the cat.