San Diego County already successfully completed an election -- a special election held on April 11 -- with a paper trail for every vote cast, said Mikel Haas, registrar of voters.

Haas noted that the statute doesn't require that voters receive personal paper confirmation of their vote. It only requires that a printed record be retained in the voting machine for use in audits.

The latest California effort is placating some critics of e-voting, who have argued that touch-screen technology is open to tampering and fraud.

"California's June primary ushers in a new era of accountability and transparency in state elections," said Kim Alexander, president and founder of the California Voter Foundation, a nonprofit voting-technology advocacy group, in a statement last month. "Election officials rely on proprietary software produced by private companies to count the votes," and a paper trail can ensure that election audits are possible, said Alexander.

Others, like Brad Friedman, whose BradBlog.com Web site covers electronic voting issues, say the California measure remains too weak. Friedman describes the audit of 1 percent of precincts as a "ridiculously" small sample.