1992: Court ordered districts
The 1990 census gave California seven additional congressional seats. Attempts by the legislature to draw up new districts were unsuccessful, as three different plans drawn up by the Democratic-controlled Legislature were vetoed by Republican governor Pete Wilson. In September 1991 the California Supreme Court took jurisdiction over the redistricting process to break the stalemate. Districts were drawn up by a panel of retired judges.
2012: Citizens Redistricting Commission
Proposition 11, a California ballot proposition known as the Voters FIRST Act, was approved by the voters on November 4, 2008. It removed from the California Legislature the responsibility for drawing the state's congressional districts, and gave the responsibility instead to a 14 member Citizens Commission. It also required that the districts drawn up
(1) comply with the federal Voting Rights Act;
(2) make districts contiguous;
(3) respect, to the extent possible, the integrity of cities, counties, neighborhoods and "communities of interest"; and
(4) to the extent possible, make districts compact. Several of these terms are not defined in law.
Governor Arnold Schwarzenegger had earlier proposed placing the redistricting process in the hands of retired judges, which was on the November ballot as an initiative in a special election (called by the Governor on June 14, 2005), Proposition 77. The special election was held on November 8, 2005. However, the initiative was overwhelmingly defeated, with 59 percent voting no. All initiatives, including those proposed by the Governor's allies and several independent initiatives, failed that year.
The California Citizens Redistricting Commission certified final district maps on August 15, 2011, and they took effect with the 2012 election. The new districts are described as more "purple" than "red" or "blue" - that is, more mixed in electoral composition compared to the mostly "safe" districts of the previous decade, where incumbents were almost guaranteed re-election. An interactive map comparing the old districts with the new ones is available via the Los Angeles Times.
https://en.wikipedia.org/wiki/California's_congressional_districts