In California, and some other states, election officials postally mail sample ballots to all voters. In partisan primaries, California election law lets parties include an envelope in the postal package, which enables members of particular parties to send a donation to that party. Of course, a Republican envelope would only be included in the mailing sent to registered Republicans.
On July 13, a California State Court of Appeals ruled that the San Diego Registrar of Voters was correct in 2010, when she let the Republican Party include not just an envelope, but electioneering material making endorsements in ballot measures and non-partisan elections. See the opinion here. The opinion takes no notice of the fact that in future California primaries for state office and Congress, there are no more partisan primaries. The opinion may have little impact on future elections anyway, because a bill is moving through the legislature that deletes the ability of parties to submit anything. Thanks to Rick Hasen for the link.
The argument given for the bill is that county election officials won’t have to expend money defending against lawsuits like this one.
The opinion does somewhat skirt around Proposition 14. The California Constitution used to forbid endorsement of non-partisan candidates, and the plaintiffs contended that the insert therefore violated the constitution. However, that provision had previously been ruled unconstitutional, which it notes. Proposition 14, explicitly removed the old unconstitutional provision.
Why would you expect that a judge would take into account passage of Proposition 14?