SAN FRANCISCO -- Saying fair, orderly elections are especially important at this "critical time in our nation's history," a federal appeals court Monday halted California's recall balloting, throwing the election into unprecedented confusion.

The decision prohibited the scheduled Oct. 7 election because error-prone punch-card voting machines would be used in six counties -- including Sacramento and Los Angeles -- that together account for 44 percent of the state's registered voters.

The court did not order the election be held on a specific date but said the public interest would best be served by holding it on March 2, 2004, in conjunction with the presidential primary election. A heavy voter turnout is expected for the primary, especially among Democrats.

The ruling, issued by a three-judge panel of the 9th U.S. Circuit Court of Appeals, also propelled the final legal battle over the recall toward the U.S. Supreme Court -- and what legal scholars called an uncertain fate.

The heart of the 9th Circuit's lengthy opinion was the Supreme Court's Bush v. Gore decision, which stopped the 2000 presidential vote recount in Florida, deciding the election in favor of George W. Bush.

"The weight given to votes in non-punch-card counties is greater than the weight given to votes in punch-card counties because a higher proportion of the votes from punch-card counties are thrown out," the 9th Circuit said. "Thus, the effect of using punch-card voting systems in some but not all counties is to discriminate on the basis of geographic residence."

The Supreme Court prohibited geographic discrimination in Bush v. Gore, said the 9th Circuit. The opinion also cited a long string of earlier cases in which the high court said the right to vote includes the right to have one's vote counted.

Citing evidence submitted by election data experts projecting the invalidation of 40,000 ballots in punch-card counties, the 9th Circuit said, "The effect is not trivial." The opinion said the margin of error could exceed the margin of victory.

Under a 2002 legal agreement, punch-card machines must be phased out throughout California no later than March 1.

Besides Sacramento and Los Angeles, the other four affected counties are Santa Clara, San Diego, Mendocino and Solano. All of them plan to use decertified, pre-scored punch-card machines, called Votomatic or Pollstar, which have been known since at least 1975 to leave "hanging chads" or to create other problems that cause a high ballot invalidation rate.

"It is perhaps ironic that the sitting governor could well cast a vote on his own recall that would not be tallied," said the 9th Circuit. The same might be true for "any candidates seeking to replace him," the judges said.

The court said the constitutional defect was compounded by the heavy presence of minority voters in the counties using punch-card systems.

The unanimous unsigned opinion in Southwest Voter Registration Education Project v. Shelley was issued by a panel made up of 9th Circuit Judges Harry Pregerson of Woodland Hills, Richard Paez of Los Angeles and Sidney Thomas of Billings, Mont.

Secretary of State Kevin Shelley on Monday sent a memo to county election officials, advising them to continue preparing for an election on Oct. 7. He also issued a public statement urging voters "to continue to register, to vote early and to vote by mail."

But Shelley, the named defendant in the case, did not disclose his plans regarding an appeal. The 9th Circuit stayed its own order for a week to accommodate one. He could appeal to either the entire 9th Circuit or the Supreme Court. Neither court is obligated to take any action, however.

Recall strategist Dave Gilliard said the recall proponents also think they have a right to appeal. Cathy Catterson, the 9th Circuit's clerk, said accepting an appeal from that source would likely be within the court's discretion.

Or any of the circuit's active judges could force a poll among all 26 of them on whether the circuit will conduct a review by 11 of the active judges, chosen at random. Catterson said she was unable to comment on whether any 9th Circuit judge had taken action to start such a poll.

Legal scholars declined to predict whether the opinion would hold up on appeal.

Vikram Amar, a Hastings College of the Law professor, called the ruling "surprising but not outlandish." "It's not flouting the Supreme Court so much as going beyond it" to say that punch cards are unconstitutional under the circumstances in California -- recording votes on fallible machines -- rather than, as in Florida, recounting votes by potentially corrupt human beings, said Amar.

UCLA law professor Daniel Lowenstein put the odds of the decision holding up at 50-50. With the election just three weeks away, he said, issuance of a Supreme Court stay beyond the expiration of the current 9th Circuit stay next week "could be the whole game."

The 9th Circuit showed "the height of irresponsibility" by imposing that kind of uncertainty on the election process, Lowenstein said.

Candidates were divided in their reactions.

Arnold Schwarzenegger said voters' rights were violated.

Arianna Huffington called the decision "very good news," saying it would give voters time to scrutinize candidates, and candidates time to register or reactivate voters.

Favoring "a result ... that allows as many Californians as possible to vote," Gov. Gray Davis said, "I do think the possibility of a small turnout overruling 8 million people (the voters who cast ballots in November) is not good for democracy. It violates the sanctity of the election process." But he declined to comment on whether a March election date would benefit or hurt his campaign.

Reaction from the recall campaign committee was bitter.

"We believe very strongly that we are right on the law, and the facts that the 9th Circuit used to come to its conclusion were all simply made up," said Thomas Hiltachk, a lawyer representing chief recall proponent Ted Costa.

But the American Civil Liberties Union, which filed the punch-card lawsuit, said the decision was "exactly what it should be." Alan Schlosser, the organization's Northern California legal director, said the ruling was based on the law, the evidence and Bush v. Gore. He predicted the Supreme Court would uphold the decision "if they're consistent with their precedent."

Praise for the 9th Circuit's ruling also came from other civil rights organizations that were involved in the case, including the Southwest Voter Registration Education Project, the Mexican American Legal Defense and Educational Fund and the California NAACP.

Art Pulaski, executive secretary-treasurer of the California Labor Federation, said, "In Florida, the Supreme Court violated our right to vote, and they owe us on this one."

The 9th Circuit decision also postponed voting on Propositions 53, regarding infrastructure funding, and 54, on state collection of race data.