21 C.F.R. § 314.90
(a) An applicant may ask the Food and Drug Administration to waive under this section any requirement that applies to the applicant under §§ 314.50 through 314.81. An applicant may ask FDA to waive under § 314.126(c) any criteria of an adequate and well-controlled study described in § 314.126(b). A waiver request under this section is required to be submitted with supporting documentation in an NDA, or in an amendment or supplement to an NDA. The waiver request is required to contain one of the following:
(b) FDA may grant a waiver if it finds one of the following:
[50 FR 7493, Feb. 22, 1985, as amended at 50 FR 21238, May 23, 1985; 67 FR 9586, Mar. 4, 2002; 81 FR 69649, Oct. 6, 2016]