At the U.S. Supreme Court’s arguments Wednesday in a major abortion rights challenge from Louisiana, the likely key to how the case is resolved—Chief Justice John Roberts Jr.—appeared focused on how closely the justices must follow their 2016 decision striking down a nearly identical law.

Roberts voted in dissent in the 2016 case, Whole Woman’s Health v. Hellerstedt, which struck down a Texas requirement that abortion physicians have hospital admitting privileges within 30 miles of their clinics. The high court majority ruled that the hospital admitting privileges requirement had no medical benefits and thus unduly burdened a woman’s access to abortion.