CAL. CCP. CODE § 877 : California Code - Section 877

Where a release, dismissal with or without prejudice, or a covenant not to sue or not to enforce judgment is given in good faith before verdict or judgment to one or more of a number of tortfeasors claimed to be liable for the same tort, or to one or more other co-obligors mutually subject to contribution rights, it shall have the following effect:

(a) It shall not discharge any other such party from liability unless its terms so provide, but it shall reduce the claims against the others in the amount stipulated by the release, the dismissal or the covenant, or in the amount of the consideration paid for it, whichever is the greater.

(b) It shall discharge the party to whom it is given from all liability for any contribution to any other parties.

(c) This section shall not apply to co-obligors who have expressly agreed in writing to an apportionment of liability for losses or claims among themselves.

(d) This section shall not apply to a release, dismissal with or without prejudice, or a covenant not to sue or not to enforce judgment given to a co-obligor on an alleged contract debt where the contract was made prior to January 1, 1988.