[Ed. – The universe saw Trump coming. State Republicans are taking it to the California Supreme Court.]
However, critics argued that the new law was unconstitutional, based on legal precedents that struck down extra requirements for the office of president that went further than the simple prescriptions in Article II of the U.S. Constitution.
In addition, the San Francisco Chronicle points out, there could be state constitutional provisions that bar the new law as well:
Forty-seven years ago, California’s voters opened the state’s presidential primaries to all nationally recognized candidates. …
[I]n 1972, 61% of the state’s voters approved Proposition 4, a state constitutional amendment, which said the presidential primary ballot must list “recognized candidates throughout the nation or throughout California,” as determined by the secretary of state.