California Code
CHAPTER 6 - Release
Section 1543.

1543. A release of one of two or more joint debtors does not extinguish the obligations of any of the others, unless they are mere guarantors; nor does it affect their right to contribution from him or her, except as provided in Section 877 of the Code of Civil Procedure.

(Amended by Stats. 1987, Ch. 677, Sec. 1.5.)