California has taken leadership in this regard by publishing CalGreen, the state's mandatory green code. But CalGreen, like LEED, is an additional layer of regulation that makes up for failures in the IAPMO and ICC model plumbing-, mechanical-, and building-codes.
California's CalGreen perpetuates a double-standard in building regulations by having three tiers of requirements. The bigger cities are enforcing the upper tiers, making LEED-equivalent the worst-allowable construction. Smaller jurisdictions may require a weak local Green Building Regulation as an alternate to CalGreen.