California Code, Government Code - GOV § 53996

The Legislature hereby finds and declares that a local agency's obligation of contract, as that term is used and interpreted in Section 9 of Article I of the California Constitution, in a financial transaction, commences when the legislative body adopts a resolution officially entering into the contract or when the treasurer, acting on his or her authority, enters into the contract.  Therefore, in interpreting Section 9 of Article I of the California Constitution, the Legislature finds and declares that no law may be passed which has the effect of impairing a local agency's existing obligation of contract with regard to a financial transaction.