Chief Justice John Roberts Jr. on Monday named Jeffrey Minear, a 20-year veteran of the solicitor general’s office, to be his administrative assistant, a position akin to chief of staff.

Minear, who has argued 56 cases before the high court, will succeed Sally Rider, who served as administrative assistant to Roberts’ predecessor, the late William Rehnquist. Rider is leaving in September to head a constitutional studies center named after Rehnquist at the University of Arizona College of Law.