22 U.S.C. § 3949
Limited appointments
(a)
A limited appointment in the Service, including an appointment of an individual who is an employee of an agency, may not exceed 5 years in duration and, except as provided in subsections (b) and (c), may not be extended or renewed. A limited appointment in the Service which is limited by its terms to a period of one year or less is a temporary appointment.
(b)
A limited appointment may be extended for continued service—
(1)
as a consular agent;
(2)
in accordance with section 3951(a) of this title ;
(3)
as a career candidate, if—
(A)
continued service is determined appropriate to remedy a matter that would be cognizable as a grievance under subchapter XI; or
(B)
the individual is serving in the uniformed services (as defined in section 4303 of title 38 ) and the limited appointment expires in the course of such service;
(4)
as a career employee in another Federal personnel system serving in a Foreign Service position on detail from another agency;
(5)
as a foreign national employee;
(6)
in exceptional circumstances if the Secretary determines the needs of the Service require the extension of—
(A)
a limited noncareer appointment for a period not to exceed 1 year; or
(B)
a limited appointment of a career candidate for the minimum time needed to resolve a grievance, claim, investigation, or complaint not otherwise provided for in this section.
(c)
(1)
Except as provided in paragraph (2) noncareer employees who have served for 5 consecutive years under a limited appointment under this section may be reappointed to a subsequent noncareer limited appointment if there is at least a 1-year break in service before such new appointment.
(2)
The Secretary may waive the 1-year break requirement under paragraph (1) in cases of special need.
( Pub. L. 96–465, title I, § 309 , Oct. 17, 1980 , 94 Stat. 2086 ; Pub. L. 100–204, title I, § 176 , Dec. 22, 1987 , 101 Stat. 1361 ; Pub. L. 103–236, title I, § 180(a)(1) , Apr. 30, 1994 , 108 Stat. 415 ; Pub. L. 103–415, § 1(hh) , Oct. 25, 1994 , 108 Stat. 4303 ; Pub. L. 114–323, title IV, § 409 , Dec. 16, 2016 , 130 Stat. 1930 .)