Even paying the penalty is effectively optional, because Congress, for political reasons, barred the Internal Revenue Service from using its most effective tools -- liens, forfeiture and prosecution -- to collect it. As The Associated Press recently explained, the IRS, confronted by uninsured taxpayers who refuse to pay the penalty, must instead resort to "scary letters and threats to withhold tax refunds."
How effective will those letters be once taxpayers realize the threats are empty? They can even avoid having the money taken out of their refunds by adjusting their withholding or estimated tax payments so that they come out even (or owe a little) at the end of the year. In practice, no refund means no penalty.
After ObamaCare was enacted in 2010, the Congressional Budget Office projected that some 4 million Americans would choose to pay a penalty in 2016 rather than comply with the health insurance mandate. Testifying before the House Ways and Means Committee last week, Steven G. Bradbury, who headed the White House Office of Legal Counsel under George W. Bush, argued that number "will be considerably greater" once people understand they have no legal obligation to buy coverage. In fact, since the penalty is essentially unenforceable, it is possible that it won't produce any revenue to speak of, which would make it an odd tax indeed.
Bradbury suggested that Congress might react to such widespread disobedience, which could make ObamaCare financially unsustainable, by increasing the penalty and authorizing the IRS to use more-intimidating tools. But that would reveal the coercive nature of the "minimum essential coverage" provision and the implausibility of viewing it as anything other than an unconstitutional order.