There seems to be an urban legend making the rounds. It says something to the effect that California's teacher-tenure-lengthening Proposition 74, should it have passed, would have also made membership in the Communist Party grounds for firing. (First heard of this one via supergee.)
I am pleased to report that California teachers did not have to fear that from the proposition.
California teachers don't have to worry about any proposition passing that language, actually. Because it's already part of the state Education Code -- Sec. 44932.a.10.