Quoting Trent W. Buck (trentbuck@gmail.com):
OK so here I don't "register to vote", because compulsory voting. Some other government department (the ATO?) dobs me in to the AEC.
Are you saying that in addition to your name and citizen ID, you also have to tell the government *in advance* who you're going to vote for?
No, at least not substantively. Individual ballot results for all elections, primary[1], general, and special, are all required to be kept secret by law, i.e., information about whom an individual voter chose is absolutely not available to anyone, zealously guarded by county and state election officials, and IIRC made impossible to reconstruct (by destruction of ballots) soon after each ballot box is certified and entered into totals. The fact that a named voter has indicated to election officials a specific party affiliation AKA 'preference' (which as you note is optional, but a game-theoretical smart move) is, by contrast, public information. E.g., the fact that I am registered Democratic Party can be looked up in California's and San Mateo County's public records. The fact that Emma Stone, Demi Moore, and a bunch of other nitwit celebrities _accidentally_ registered themselves AIP (because they're stupid) is likewise public data, hence their recent mocking by the _LA Times_ and subsequent fumbled excuse-making. But this doesn't actually tell you whom Demi Moore, Emma Stone, etc. ever voted for -- not at all -- only which set of primary election candidates they were eligible to vote for, at the time you checked the voter rolls. Knowing that I'm registered Democratic would strongly suggest to you that I'll probably vote for either Clinton or Sanders in the June 7th California primary election (though there are also several other minor Democratic Party candidate on that ballot, and IIRC write-ins are also permitted). But you wouldn't know which one, except I've said I'm a Sanders support -- albeit a voter worried about fallout (bosses, family, trade unions, etc.) from a selection is perfectly free to lie. Or to say nothing, because after all it's nobody else's business. Nor would you have more than a hunch about whom I'd vote for in the November general election, where any voter may vote for any entry on the ballot, or for write-ins. But you could certainly guess I'd vote Clinton, and would be correct. [1] I think I might have mentioned that the 'caucus' method used by some states such as Nevada instead of a primary election does tend to prevent secret balloting, which is deemed a huge and damning flaw in that method (unless modified to render the voting phase at the end of caucusing secret, as the Nevada Republican Party does to its credit and the Nevada Democratic Party does not). This is part of the reason why the caucus method has become rarer over the country's electoral history.