Sometime in the next six weeks, the U.S. Supreme Court will decide Arizona Legislature v Arizona Redistricting Commission, 13-1314. This article says that if the U.S. Supreme Court rules in favor of the Arizona legislature, that would probably be good news for the Republican Party in Arizona but bad news for the Republican Party in California.
If the California legislature tried to redistrict, the Republicans would petition for a referendum. When a referendum is lodged, the legislation does not go into effect.
In the past when this has happened, the California Supreme Court has let the legislative enactment be used – but in those instances it was immediately after reapportionment, and there was no other plan with the correct number of congressional districts.
That is not the case, since there are two plans with 53 congressional districts: the plan drawn by the redistricting commission; and the plan drawn in 2001 by the legislature. The plan would be found to violate OMOV.
Faced with an election with no lawful plan, a federal or California Supreme Court will use the plan drawn by the redistricting commission rather than one that is malapportioned or subject to a referendum.