Krugman is upset this week at a judicial ruling that held that the government's case for naming MetLife a Systemically Important Financial Institution (SIFI) was inadequate and should be thrown out. Sure, it's impossible to nail down what the criteria for a SIFI are, says Krugman, but so what? We take on the whole issue -- not just MetLife, but the whole idea of extra regulation for so-called SIFIs.