The Ninth Circuit has upheld California laws that mandate the disclosure of contributions to ballot measure campaigns (see here and here). But Buckley v. Valeo (1976) and Brown v. Socialist Workers' 74 Campaign Committee (1982) held that "the First Amendment prohibits the government from compelling disclosures [of campaign contributions] by a minor political party that can show a 'reasonable probability' that the compelled disclosures will subject those identified to 'threats, harassment, or reprisals.'"

Presumptively, the same rule should apply as to compelled disclosures of contributions to ballot measure committees -- but does it apply even when the ballot measure may well win (as opposed to a "minor political party," which is nearly sure to lose)?

Relatedly, just how much of a showing of "harassment" and "reprisals" would opponents of same-sex-marriage have to show in order to justify such an exemption? I take it that the theater boycott incident I mention below wouldn't by itself suffice, nor would it if it's coupled with the hotel boycott we blogged about a few months ago. But, given Brown, how many such incidents -- or what types of incidents -- would be required? Does there have to be evidence of violence, police abuse, or firings by employers? Or would evidence of public boycotts of the contributor's business, or the contributor's employer, qualify?