As far as I can tell, Obamacare cannot be effectively nullified by the states. Congress was smart (devious) enough to use the tax system to implement things. What Obamacare did was place a tax on every person in the US. If you get health insurance, they'll give you a tax credit to offset the charge. There will be no one checking to see if you have health insurance and fining those lacking - we essentially have to ask congress for the credit when we file our taxes. There is nothing for the states to nullify, no way I can see to get around this. Congress has the power to tax, and the most we can do is to not accept their tax credit if we have insurance - which no one will do. Nullification can't affect Obamacare at all.