The media is filled with articles and reports on this week’s Supreme Court arguments on the Affordable Care Act. This WSJournal article (subscription required) efficiently summarizes the arguments and justices’ questions. Definitions of the relevant economic activity reveal a key distinction between the law’s challengers and supporters–the former focus on the market for health insurance, the latter on the market for health care. The two are obviously connected but the law’s opponents argue that one can be in the market for the latter without being in the market for the former. The media consensus is that the law is in trouble–on CNN Jeffrey Toobin called the Supreme Court session “a train wreck for the Obama administration–and that Justice Kennedy is the key.