Say goodbye to Obamacare...

[Yo_Mama]

55. The Federal government cannot order state governments to do that under the Constitution

That's very clearly established. The Federal government has broad powers to regulate under the Commerce Clause, and when it does its laws preempt those of the states. But the Federal government does not have the power to directly control state governments - that's a sovereignty issue. So most such laws involve a fiduciary incentive, such as additional funds in exchange for seatbelt laws, etc, to get state governments to fall in line.

If Congress could mandate that state governments set up insurance exchanges, it could in effect literally take over state governments by telling them what else to do. That the courts have held is an unconstitutional violation.

The federal government can make drugs illegal under the Commerce Clause. But it cannot force states directly to, say, spend a certain amount of money on drug enforcement, or mandate that state governments set up a registry of persons found with those illegal drugs. It cannot force California to conform its drug laws to the federal drug laws!

In Printz, for example, some provisions of the Brady Bill were struck because they required state or local LEOs to enforce federal law:
http://www.law.cornell.edu/supct/html/95-1478.ZO.html