A ballot measure restricting campaign contributions became the target of its first lawsuit one week after it passed at the polls.
The California Prolife Council's Political Action Committee sued in federal court Tuesday, calling Proposition 208 unconstitutional.
Proposition 208 backers said they expected lawsuits.
"We have said all along that when you drain the swamp, the alligators will get angry," said Tony Miller of the Yes on 208 campaign. "This is probably just the first of many lawsuits against campaign finance reform that will be brought by defenders of the status quo."
The lawsuit charges that Proposition 208 violates the constitutional protections of free speech and due process, said Thomas Hockel, an attorney for the California Prolife Council's Political Action Committee.
"To the extent that the alligators' 1st and 14th amendment [to the U.S. Constitution] rights are being violated, they should be angry," he said.
Voters overwhelmingly approved the ballot measure last week and rejected Proposition 212, a rival attempt to restructure the state's campaign finance system.
Californians also approved contribution limits in 1988, but federal courts struck down those restrictions, ruling that they favored incumbents.
Proposition 208 allows an individual or group to give up to $250 per election to a legislative candidate and up to $500 to a statewide candidate per election.
So-called small donor committees--groups of 100 or more people who each contribute no more than $50--can give twice those amounts.
The donation limits for local candidates depend on the number of people in their districts.