After giving $10,000 to California's Proposition 8 campaign last year, Charles LiMandri began receiving some unexpected correspondence.
"I got about two dozen e-mails and hate phone calls," said Mr. LiMandri, who lives in San Diego. "They were calling me Nazi, homophobe, bigot. I tried to engage people once or twice - I said that Proposition 8 had nothing to do with being bigoted, it was about preserving marriage - but people don't want to engage on the issue."
As a lawyer, however, Mr. LiMandri knew what to do with the e-mails.
"I collected them and turned them in to the lawsuit," he said.
Those e-mails are now among hundreds of exhibits in a landmark case challenging California's campaign-finance reporting rules, which require the release of the names, addresses and employers of those who contribute $100 or more to ballot-measure committees.
The lawsuit argues that those who contribute to traditional-marriage initiatives should be exempt from having their names disclosed, citing the widespread harassment and intimidation of donors to the Proposition 8 campaign.
Proposition 8, which stated that California would recognize marriage only between a man and a woman, was approved 52 percent to 48 percent in November. The initiative overturned a California Supreme Court decision in May declaring that the state's marriage definition unconstitutionally discriminated against gays.
Intimidation tactics range from letters and e-mails to death threats, proponents say. A Sacramento theater director was fired after opponents of the initiative publicized his Proposition 8 campaign contributions.
"Anybody who's in California knows that it's very widespread," said Brian Brown, executive director of the National Organization for Marriage, one of the biggest contributors to Proposition 8 and a joint plaintiff in the lawsuit. "Every donor has a story. I talked to a $100 donor the other day who had a note in his mailbox that said, 'I know where you live and you're going to pay.'
"These are just hardworking people who believe marriage is a union of a man and a woman and who never expected to be threatened in their homes," Mr. Brown said.
Leading the effort is Californians Against Hate - whose Web site, www.californiansagainsthate.com, lists the names of 1,100 people and organizations contributing at least $5,000 to the Proposition 8 campaign. The list, compiled from information supplied by the California secretary of state's office, also gives addresses, phone numbers and Web site addresses.
The group also has organized a series of boycotts targeting large donors, including the owner of three hotels who contributed $125,000 to Yes on Proposition 8, and a storage company whose owners gave $700,000.
While Californians Against Hate has focused on major donors, other groups have shown less restraint. Several Web sites use online maps to pinpoint the home or office locations of all known Proposition 8 donors.
Fred Karger, who launched Californians Against Hate in July, acknowledged that intimidation is part of the political strategy.
"One of my goals was to make it socially unacceptable to make these mega-donations that take away people's rights," Mr. Karger said. "I want them to think twice before writing that check."
Those crying foul have either short or selective memories, he said. In 1978, donors to the campaign against California's Proposition 6, which would have banned gays from working in the state's public schools, also risked being harassed, fired or blacklisted. Proposition 6, better known as the Briggs Initiative, failed by a margin of 58 percent to 42 percent.
"When I gave $100 to fight Proposition 6, you risked it all," said Mr. Karger, adding that the donation nearly cost him his job. "It was a very scary time. Gay people have been going through this for decades. Now our opponents are getting a taste of what it's like."
Mr. Karger called the lawsuit a "despicable act," saying it was being pushed the Church of Jesus Christ of Latter-day Saints to conceal its financial stake in the campaign.
"They took over the Proposition 8 campaign and ran it, and now they're trying to cover up their involvement, which they can't do in California," he said.
The church has denied any role in the lawsuit.
"The Church of Jesus Christ of Latter-day Saints was not aware of the filing of the lawsuit nor was the church consulted on its filing," said Michael Purdy, a spokesman at the Mormon Church's world headquarters in Salt Lake City.
There's a precedent for exempting certain groups from campaign reporting requirements. In 1979, the Supreme Court agreed to lift disclosure rules for contributions to the Socialist Workers Party, saying that revealing the names of the party's donors would subject them to attacks.
The Proposition 8 lawsuit lost the first round in January when a federal judge refused to grant a preliminary injunction to stop the state from releasing the identities of those who made campaign donations after Oct. 18.
That means all the names of those who gave at least $100 to the Proposition 8 campaign already have been released. For proponents, however, the real point of the lawsuit is to protect donors in future marriage campaigns.
"We want the court to say it was wrong for the state to force the disclosure of donors when they faced intimidation," Mr. Brown said. "If another proposition comes up, we'd have to file again, but we'd have the precedent."