5 U.S.C. § 5106 — Basis for classifying positions

(a) Each position must be placed in its appropriate class. The basis for determining the appropriate class is the duties and responsibilities of the position and the qualifications required by the duties and responsibilities. (b) Each class must be placed in its appropriate grade. The basis for determining the appropriate grade is the level of difficulty, responsibility, and qualification requirements of the work of the class. (c) Appropriated funds may not be used to pay an employee who places a supervisory position in a class and grade solely on the basis of the size of the organization unit or the number of subordinates supervised. These factors may be given effect only to the extent warranted by the work load of the organization unit and then only in combination with other factors, such as the kind, difficulty, and complexity of work supervised, the degree and scope of responsibility delegated to the supervisor, and the kind, degree, and character of the supervision exercised.