California Code
CHAPTER 3 - Civil Provisions of General Application
Section 5700.315.

5700.315. A party whose parentage of a child has been previously determined by or pursuant to law may not plead nonparentage as a defense to a proceeding under this part.

(Added by Stats. 2015, Ch. 493, Sec. 5. (SB 646) Effective January 1, 2016.)