5 U.S. Code § 3101
5 U.S. Code § 3101 is about General authority to employ. It is under Part 3 (Employees) Subpart B (Employment and Retention) Subchapter 1 (Employment Authorities) Chapter 31 (Authority For Employment) of Title 5 (Government Organizations and Employees) of the Code.
Each Executive agency, military department, and the government of the District of Columbia may employ such number of employees of the various classes recognized by chapter 51 of this title as Congress may appropriate for from year to year.