SAN FRANCISCO (AP) - California's Supreme Court is having doubts about the privacy of overseas ballots cast via facsimile, but won't weigh in on the dispute until after the Nov. 2 election.

The high court was considering a challenge to a Sept. 27 California law allowing overseas voters to fax their votes if they waive their rights to "keep my ballot secret." The justices were asked immediately to halt the privacy waiver requirement on grounds that it violated the state constitution, which says "voting shall be secret."

But the justices said they would not act immediately for fear of skewing election returns.

"We conclude that it is impossible, as a practical matter, to provide interim relief with regard to the upcoming election without engendering undue confusion and uncertainty in the election results," the court said in a Friday order made available Monday.

Instead, the court ordered California Secretary of State Kevin Shelley to answer - after the election is certified - why his office should be allowed to require the waiver. If voters don't sign the waiver, their vote does not count.

Tony Miller, a special counsel to Shelley, said it is impossible to have private voting when done by fax. He said voters must sign the waiver "so the voter can contemplate whether they want to take that risk."

"I don't think anybody has come up with a way to assure with 100 percent certainty that a faxed-back ballot would not be compromised in terms of secrecy. It's inherent in the faxing process," he said.

The lawsuit was brought by three overseas California voters, one of them on undisclosed military duty. They say the possibility that their votes won't be kept secret has kept them from voting.

The 600,000 military and civilian overseas California registered voters can fax their ballots in two different ways. One is directly to their county election office, where officials are sworn not to divulge voter choices.

The Federal Voter Assistance Program run by the Department of Defense also assists overseas voters. But for military or civilian voters to fax a ballot through that toll-free service, which is administered by a private contractor, they also must waive their right to privacy.

The lawsuit says California overseas voters have no method of secretly casting an overseas ballot by fax.

"Privacy is a constitutional requirement that the Legislature can't change," said attorney Scott Rafferty, who is representing the three overseas voters.

Rafferty is a lawyer for John Kerry's campaign in California.

The case is Bridgeman v. Shelley, S128311.