What will be argued on Thursday is that what was voted on — the ACA — was indisputably a revenue measure and unquestionably did not originate in the House, which later passed the ACA on another party-line vote.

This case comes from Matt Sissel, an Iowa artist and small-business owner who is represented by the Pacific Legal Foundation, which litigates for limited government. Sissel neither has nor wants health insurance, preferring to invest his limited resources in his business. Hence he objects to the ACA’s mandate that requires him to purchase it or pay the penalty that the ACA daintily calls the “shared responsibility payment.”

In June 2012, a Supreme Court majority accepted a, shall we say, creative reading of the ACA by Chief Justice John Roberts. The court held that the penalty, which the ACA repeatedly calls a penalty, is really just a tax on the activity — actually, the nonactivity — of not purchasing insurance. The individual mandate is not, the court held, a command but merely the definition of a condition that can be taxed. The tax is mild enough to be semi-voluntary; individuals are free to choose whether or not to commit the inactivity that triggers the tax.