California's secretary of state, Debra Bowen, believes that open-
source software should be used in elections involving electronic
voting machines, to protect against error and fraud.

....the biggest concern, according to Bowen, is a lack of access to the
machines' underlying code. "Many times, a person has no legal right to
review the software, even if they could," she said.

The [commissioned by Bowen] study revealed a variety of problems, from
software vulnerabilities that could let an attacker install malicious
software that changes the outcome of a vote, to opportunities to
tamper with the devices while they are held in storage....

When asked about future elections, Bowen said the one technology she'd
like to see integrated into voting systems tomorrow is open-source
software for creating ballots and tabulating votes....

"A lot of the concern comes out of the fact that no one can look at
the software," Bowen says. She notes that voting-machine analysis
often has to be performed under a nondisclosure agreement, meaning
that the details of some flaws remain undisclosed.