It is widely recognized that Big Law has surplus partner capacity. In a recent Altman Weil survey, over two-thirds of firm leaders reported their equity partners were not sufficiently busy; nearly 80 percent said the same of nonequity partners. What is less well recognized is just how massive this surplus has become, how unevenly it is spread across firms in different profitability cohorts, and what it portends for when the next downturn hits.