Until now, when it's time to go to court and defend it. Now, the administration is defending mandating participation under penalty of a stiff fine by saying ObamaCare come under the federal government's power to tax:
Administration officials say the tax argument is a linchpin of their legal case in defense of the health care overhaul and its individual mandate, now being challenged in court by more than 20 states and several private organizations.
Under the legislation signed by President Obama in March, most Americans will have to maintain “minimum essential coverage” starting in 2014. Many people will be eligible for federal subsidies to help them pay premiums.
In a brief defending the law, the Justice Department says the requirement for people to carry insurance or pay the penalty is “a valid exercise” of Congress’s power to impose taxes.
Congress can use its taxing power “even for purposes that would exceed its powers under other provisions” of the Constitution, the department said. For more than a century, it added, the Supreme Court has held that Congress can tax activities that it could not reach by using its power to regulate commerce.
The Administration is trying to get lawsuits against ObamaCare's legality dismissed by claiming it's a tax bill because federal law requires that the taxes be paid first before any adjustments are made.
However, that's only an argument on the penalty, which doesn't address the 5th amendment issue of a governmental taking of private property.
Even more egregiously, ObamaCare is requiring people to buy goods and services from private entities. That's not a tax - it's forcing Americans to engage in compelled economic activity and forced private contracts.
No court has ever found any Constitutional authority for the federal government to force that sort of thing - so far.