California Code, Health and Safety Code - HSC § 19166

Any building identified as being a seismic hazard to life and retrofitted in compliance with building seismic retrofit standards adopted pursuant to this article and properly maintained, shall not, within a period of 15 years, be identified as a seismic hazard to life pursuant to any local building standards adopted after the date of the building seismic retrofit unless the building no longer meets the seismically hazardous building retrofit standards under which it was retrofitted.