Congress is not empowered to tax for those purposes which are within the exclusive province of the States. Justice John Marshall, Gibbons v. Ogden, 1824.
In fact, Sen. Rubios Constitution-oblivious tax plan is a good example why the ill-conceived 17th Amendment should never have been ratified, state lawmakers foolishly giving up their voices in Congress by ratifying that amendment.
The 17th Amendment needs to disappear.
Does anyone recall Steve Forbes?