US Code Title 5 § 2102

§ 2102. The competitive service

(a) The “competitive service” consists of— (1) all civil service positions in the executive branch, except— (A) positions which are specifically excepted from the competitive service by or under statute; (B) positions to which appointments are made by nomination for confirmation by the Senate, unless the Senate otherwise directs; and (C) positions in the Senior Executive Service;