“When does it end?” That question dominated marathon arguments Monday in the U.S. Supreme Court as the justices considered challenges to race-conscious admissions policies at the University of North Carolina and Harvard College.

The justices heard roughly five hours of arguments in two challenges brought by a long-time opponent of racial preferences, Edward Blum, director of the Project on Fair Representation. In both cases, Students for Fair Admissions, an organization created by Blum, is asking the high court to overrule its 2003 decision in Grutter v. Bollinger upholding the use of race as a factor in a holistic review of student applicants at the University of Michigan Law School.