Obamacare's future is once again in jeopardy, thanks to one of the law's most stubborn opponents — the U.S. Constitution. Twenty states are suing the federal government in Texas on the grounds that, since Congress zeroed-out the penalty for the individual mandate, the law is no longer constitutional.

They're right.

The U.S. Supreme Court deemed the individual mandate constitutional back in June 2012 by interpreting the provision as a tax — something Congress clearly has the power to impose. But the tax reform law enacted in December 2017 reduced the penalty for not having coverage to zero dollars, starting in 2019. So, as a matter of fact, there's no longer a tax for those going without insurance coverage.

This, the plaintiffs argue, means that the defense that allowed Obamacare to survive six years ago no longer applies. And that makes the mandate unconstitutional.

The lawsuit also claims that the individual mandate is not "severable" from the rest of the law. The only way to bring Obamacare into compliance with the Constitution, it follows, is to do away with the law entirely. Four Supreme Court justices agreed during the 2012 case; the plaintiffs only need to pick up one more vote to win this time around, and they might just find it if Chief Justice John Roberts rules against Obamacare after ruling in its favor in the 2012 case.

The individual mandate marked the first time in American history that the federal government required the purchase of a product as a precondition for residing in the U.S. Nowhere does the Constitution give Congress the power to issue such a mandate. It's remarkable that the provision — and the law which turns eight on March 23 from which it is not severable — has lasted as long as it has.

If the latest case manages to topple the law, as it should, then it will be because Obamacare's disregard for the Constitution finally caught up with it.

Sally Pipes (@sallypipes) is a contributor to the Washington Examiner's Beltway Confidential blog. She is president, CEO, and Thomas W. Smith Fellow in Health Care Policy at the Pacific Research Institute. Her next book, "The False Promise of Single-Payer Health Care" (Encounter), will be published this spring.