Carr's four-year tenure has been scarred by a series of embarrassing gaffes that have led detractors to question her judgment and ethics.
She was criticized when her husband, a retired police lieutenant, became a paid consultant for a murder victim's family in a case Carr's office would eventually prosecute.
But her husband consulted on a civil action against the bank where the victim was killed and had nothing to do with the criminal case, Carr said during a recent interview.
In April 2008, she was accused of intervening in a case on behalf of a defense attorney who contributed to her 2006 election campaign — which she has denied.
Rosen has seized on those criticisms, once calling her "un-American" during a candidates' forum because of her rare boycott of a judge whom she said was biased against prosecutors.
But Carr isn't taking the attacks complacently. Rosen was taken to task for prosecutorial misconduct in a trial by an appeals court eight years ago, Carr said during a March campaign debate.
She recently filed a lawsuit against the wording of Rosen's ballot statement. And she accused his campaign of taking an illegal in-kind $17,000 campaign donation from the San Jose Mercury News, after Rosen used the paper's stories on his Web site without authorization.
Rosen said he did not know it is illegal to post copyrighted articles from a newspaper's site, he told the online news site San Jose Inside.
He is questioning Carr's use of 21 billboards paid for with state money on behalf of the state's campaign against workers' compensation fraud, to which she added her name. Carr has denied the billboards have anything to do with her election campaign.
Amid the verbal brawling, both candidates claim they want to reform the District Attorney's office.
Carr, 57, a Santa Clara County Superior Court judge for six years, was elected after a three-year expose in 2006 by the Mercury News, "Tainted Trials, Stolen Justice," which uncovered widespread judicial, defense and prosecutorial failures and misconduct that the newspaper asserted deprived defendants of fair trials in Santa Clara County.
"I left the Superior Court bench to change the culture and to have a broader view of justice," she said during an interview.
She appointed an ethics advisor to aid deputy district attorneys and provide ethics training; set up capital-case protocol for consideration of death-penalty cases and established an equal-justice task force to look at the disproportionate prosecutions of minorities.
Carr set up standards and professional-development evaluations for managers. She ordered the first outside management audit in the history of the District Attorney's office, she said.
She has also gone after white-collar crime, beefing up prosecutions of mortgage and real estate fraud. Her office helped get legislation passed that made mortgage fraud a felony, she said.
"We're doing more regional kinds of things than just try cases," she said, pointing to preventive tactics to reduce gang violence, such as the Parent Project, a 13-week program that focuses on skills to help parents work through issues with adolescents, she said.
Rosen, a 15-year prosecutor of high-profile murder and sex-crime cases, has tried more than 65 jury trials and has one of the highest conviction rates in the District Attorney's office, he said. He worked in private practice for two years prior to joining the DA's office.
He has campaigned as a reformer who is intent on restoring integrity to the District Attorney's office and would create a conviction-integrity unit. The unit would handle requests to look into old and possibly wrong convictions, he said.
"A prosecutor's job is to pursue justice, not just rack up convictions," he said during a recent interview.
Rosen said he would increase transparency and open discovery to defense attorneys and supports opening the grand jury in cases involving police officers accused of crimes.
Rosen would also re-open an independent cold-case unit closed by Carr. He criticized her decision to add two public-information officers (PIO) instead.
Liquidating the unit hurt the District Attorney's office and left hundreds of unsolved rapes, robberies and murders without follow-up, he said.
Carr defended her decision, saying that prosecutors were handling media inquiries before.
"A PIO costs one-third of an attorney to get information to people," she said.
The office has faced unprecedented challenges under her watch, including an $11.7 million cut from her budget, state-mandated early releases of prisoners and a proliferation of marijuana dispensaries, she said.
Carr has managed 500 employees, an $85 million budget and 45,000 cases annually, while Rosen has no managerial experience, she said.
"It's really about who is the most experienced and most able to lead the D.A.'s office," she said.
Rosen said Carr is unfit for re-election.
Carr has come under fire in the press for deciding not to prosecute the 2007 high-profile De Anza rape case. In March, she announced her decision to not indict police officers involved in the videotaped beating of Phuong Ho, a 21-year-old San Jose State University student.
And she was widely criticized for boycotting Judge Andrea Bryan, whom she accused of bias against prosecutors. In January, Bryan had released a child molester from prison after ruling that a trial prosecutor gave false testimony in the case.
Rosen lambasted Carr's decision to instruct prosecutors to stop bringing criminal cases before Bryan, saying the boycott threatened the independence of the judiciary and eroded the checks and balances of judicial oversight of unfair prosecution.
Carr said the unusual step is allowed under state law, and that Bryan exhibited bias in several cases that prosecutors clearly should have won. She had asked that Bryan be moved to another court, she said.
Rosen said he would have appealed Bryan's decisions.
Rosen has won support from the Santa Clara County Deputy Sheriff's Association and the Santa Clara County Bar Association, the latter of which had endorsed Carr in 2006.
Carr has received endorsements from San Jose Police Officer's Association and the Central Coast chapter of the Police Officers Research Association of California.