For instance, the Constitution of 1787 allowed for direct taxation. Congress could have passed a tax of $5 per person to pay the national debt at the time, for it was clearly necessary. Congress could NOT issue general warrants for federal tax collectors to enter each and every home in order to collect the tax because the IVth Amendment prohibits general warrants.
Even if Obamacare is necessary to implement an enumerated power (it isn't), it must be proper. That means it may not violate another portion of the Constitution, which it does, the Ninth Amendment.
It is a two fold test, both necessity and propriety are required.
Here is a thorough analysis of the necessary and proper clause by Randy Barnett.
That point has already been settled by the court in Gonzales vs. Raich.
That means it may not violate another portion of the Constitution, which it does, the Ninth Amendment.
Gonzales (and a lot of precedent prior to that!) does exactly that! It establishes that almost ANY activity can be deemed to fall under the commerce clause AND that these types of activities are "never more than one step away from interstate commerce".
The court has repeatedly found that the constitution does not mean what it black letter says, but rather that it means what the COURT says it says! We likely face a 4-4 split with Scalia, who penned the "never one step away" clause being the decider. THAT does not make me comfortable!