California Code, Civil Code - CIV § 2782.5

Nothing contained in Section 2782 shall prevent a party to a construction contract and the owner or other party for whose account the construction contract is being performed from negotiating and expressly agreeing with respect to the allocation, release, liquidation, exclusion, or limitation as between the parties of any liability (a) for design defects, or (b) of the promisee to the promisor arising out of or relating to the construction contract.