Up or out is law, not policy. 10 U.S.C. § 632. It also does not necessarily "require[]" discharge for twice failing of selection for promotion; officers can be

Up or out is law, not policy. 10 U.S.C. § 632. It also does not necessarily "require[]" discharge for twice failing of selection for promotion; officers can be continued on active duty. 10 U.S.C. § 637; SECNAVINST 1920.7B.