ELEC §21623: (a) If the boundaries of a city expand by the addition of new territory, including through annexation of unincorporated territory or consolidation with another city, the council shall add that new ter

(a) If the boundaries of a city expand by the addition of new territory, including through annexation of unincorporated territory or consolidation with another city, the council shall add that new territory to the nearest existing council district without changing the boundaries of other council district boundaries. (b) Notwithstanding subdivision (a), the council may adopt new boundaries for each council district pursuant to Chapter 2 (commencing with Section 21100) if the boundaries of the city expand by the addition of new territory and if both of the following conditions are met: (1) There are more than four years until the council is next required to redistrict pursuant to Section 21621. (2) The population of the new territory being annexed or consolidated is greater than 25 percent of the city’s population as determined by the most recent federal decennial census. (c) This section does not apply to a charter city that has adopted, by ordinance or in its city charter, a different standard for adding new territory to existing council districts.