Last month, constitutional law expert Josh Hawley visited with Show-Me Institute supporters to discuss a wide array of health care policy issues. While he was with us, he offered some great insights into this Wednesday's King v. Burwell oral arguments.

If you're short on time, however, the case deals with what happens when a state declines to set up an insurance exchange under Obamacare, forcing the federal government to do so instead. Here's the big question in King: Does the Affordable Care Act (ACA) block federal subsidies from going to insurance plans purchased in government exchanges that were not, as the law says, "established by the State"? If the answer is yes, it could simultaneously take subsidies away from millions of insurance plans and protect millions of taxpayers from the law's mandates. It'd be a body blow to the law.

Why would Congress condition subsidies on states building their own exchanges? The answer is reasonably straightforward: Congress didn't want the burden of creating exchanges to be on the federal government—that is, Healthcare.gov—and thought offering the subsidy as a carrot would get states to do the heavy lifting. Congress never thought the federal government would be running the exchanges for basically two-thirds of the country, as it's doing today. Healthcare.gov's rollout disaster was part and parcel of this miscalculation by Congress.

Supporters of Obamacare now contend the "established by the State" language was a drafting error, but there is lots of evidence that runs against that claim. The state exchange "carrot" strategy had appeared in prior, contemporaneous bills that were combined to form the ACA—suggesting that at least some legislators were well aware of the system they were creating. In fact, in the years that followed, Obamacare architect Jonathan Gruber famously repeated what the consequences of states not building their own exchanges would be.

With most states declining to create their own exchanges, the Internal Revenue Service then wrote rules that would extend the federal subsidies not only to exchanges "established by the State," but also to federal exchanges. The problem is that since the federal subsidies are the basis for penalties that, thanks to the IRS, would suddenly apply to tens of millions of Americans in states that didn't create exchanges, those subsidies could be an illegal tax. Thus, we have the King litigation.

After Wednesday's oral arguments, we'll likely see a decision handed down on the case sometime this summer. How will it turn out? We'll keep you posted.