But none of that is enforceable. Once the data is released, you simply can’t control what happens to it.
I guess in practice California’s regulation must be working - based on the fact that CA data isn’t on that site i.e. maybe that site is genuinely worried that CA authorities will come after them whereas some other states are more slack about protecting data and privacy. ??
FWIW, here there is legal requirement that a political party has a minimum number of members who are eligible to vote. The relevant electoral roll gatekeeper can demand that a party provide a subset of their membership data to the gatekeeper for the purposes of that audit. The gatekeeper will then confirm that the purported party member is on the electoral roll and, if so, contact each purported party member in order to confirm with the member that they are indeed a member of that party.
However a party can choose precisely how many membership records to provide - based on the minimum number divided by the response/success rate, plus a margin for safety - and they will then themselves contact each member badgering them to make sure that they respond when contacted by the gatekeeper. A large political party would only need to provide a small fraction of their total membership data. In any case, this membership data is never legitimately made available to the public.
Voters…ordinary voters…in the US can generally specify a party affiliation. (What I say here might not be true in every single state.) Traditionally that gave them the right to participate in that party’s process to nominate candidates for public office. There are caucuses (where the party members in a single precinct meet) and primaries (basically, run a lot like elections). However, this is in flux lately; many states have mandated primaries open to non-party members to one degree or another, some let voters who did not specify a party to pick one on primary day and vote in its primary, some let people of any affiliation vote in any primary, and some have gone to a “jungle primary” where all of the partys’ candidates are put on the same ballot and the top four (or thereabouts) proceed to the general election (which means that possibly, every candidate on your general election ballot will be from the same party).
However, party affiliation or not, the voter can vote for anyone in the voting booth; there’s no way to stop them or even know if they did it. So, although you can say that Democrat voters generally vote Democrat and it’s likely to be true, you can’t say for sure about any particular voter who is registered as a Democrat, or whether they did so during the last election.
So in general, it’s a voluntary way for a voter to claim that they prefer one party over another and they can then participate in that party’s nomination process or even run to become a party official.
And voters registered as undeclared, in the Primary election in many states, get ballots without the various parties’ candidates on them; they can vote for most other state and local offices, ballot measures, etc.
During the general election that follows the Primary later in the year, undeclared voters do get to vote the full ticket.
I was trying to keep it at least somewhat simple for Irvine Wade, who wanted to know what party affiliation means here. (I infer he’s not from the United States.)
What you said only applies if there’s a general election (for some offices) being run concurrently with the primary (for other offices). That’s two different election cycles overlapping.
Sometimes in my state there will be bond measures and referenda in conjunction with a primary. Those aren’t offices, but rather voters deciding an issue, so they are important! (In fact, I usually have to choose between two or more utterly and equally worthless individuals, so sometimes those bond measures and referenda are the only worthwhile reason to vote.)
At the end of the day, what happens to the data (where it goes, who has access to it, what is done with it) is the main thing. It does sound like there are a lot of scenarios to consider, and in particular the complication that the exact rules vary between states.