Close to noon on March 26, the first day of history-making arguments in the health care cases, journalists will emerge from the U.S. Supreme Court to breathlessly report on what the justices and advocates said about the Anti-Injunction Act.

Soaring arguments about the individual mandate and the Constitution’s commerce clause will wait for another day. In the first high court face-off over the law, the justices will be preoccupied with a decidedly less glamorous — but crucially important — issue; namely, whether the challenges can proceed at all in light of a once-obscure federal statute that bars suits against federal taxes before they are collected.