The Patient Protection and Affordable Care Act, now two years old, is 1200 pages long and has countless provisions. Many of them have already taken effect, but much more change is to come over the next two years, most famously the so called individual mandate. In 2014, almost every US citizen will be required to buy health insurance, and companies of 50 or more employees will be required to offer it to their workers. In both cases, non-compliance results in a fine.

For three days in late March, the US Supreme Court listened to arguments on four issues that had been raised in lower court rulings on the law. In a circus atmosphere (demonstrators, presidential candidates, paid queue sitters) in the plaza outside the Greek temple that houses the court, and before an audience of luminaries inside, standing room only, the nine justices grilled (some would say filleted) the lawyers for both sides of the issues.

Four of the court’s justices, appointed by Republican presidents, are reliably conservative, and four, appointed by Democrats, are …