"The release of confidential e-mails may have a chilling effect on the governor's ability or willingness to solicit advice, or to accept unsolicited advice in the future," the appeals court wrote.
Corzine and his former girlfriend, Carla Katz, have been fighting to keep the e-mail exchanges private since Republican State Committee Chairman Tom Wilson and several news organizations, including The Associated Press, requested the correspondence.
"I'm pleased with the decison," Corzine told reporters outside his office Monday. "I think the courts unanimously came to the conclusion that we have properly invoked executive privilege."
Wilson called on the Democratic governor to make good on his promise of government transparency by releasing the e-mails. If he doesn't, Wilson said he would appeal Monday's decision to the state Supreme Court.
Corzine's office would not say whether he plans to release the e-mails.
The ruling came on the eve of Corzine's State-of-the-State address and threatened to overshadow the annual speech.
"We're certainly disappointed in the decision," said GOP lawyer Mark Sheridan. "It seems to grant the governor the absolute privilege to act in secrecy."
Katz said she was gratified at the outcome.
"Hopefully, we can now move forward and focus on the real and serious issues facing working families in New Jersey," she said.
Attorney General Anne Milgram, who argued the case for Corzine on appeal, called Monday's ruling "significant."
"Executive privilege is essential to the ability of Gov.
Corzine and all future governors to perform their duties and be able to receive and solicit advice from diverse sources," Milgram said in a statement.
The appeals court was swayed by Corzine's contention that the e-mails are privileged, a concept that allows officials to withhold certain information in the interest of governing. The panel was not persuaded by Wilson's argument that the public could decide, by viewing the e-mails, whether the governor and Katz acted appropriately during contract talks with the state worker unions.
"Stripped to its basic terms, Wilson has articulated no more than a suspicion of conduct that may reveal flawed judgment but does not implicate criminal misconduct," the court wrote.
Milgram argued that Corzine would not be able to govern effectively if his private communications were open to the public.
Sheridan said the public has a right to view e-mails the governor's office and Katz exchanged during state worker contract talks.
He sought disclosure of all e-mails and attachments between the governor or his staff and Katz that were not strictly personal or concerned general state business.
Wilson questioned whether state worker contract negotiations were tainted by the relationship between Corzine and Katz, who dated before Corzine became governor in 2006. She is president of the largest state worker local, Communications Workers of America Local 1034.
CWA relieved Katz of her duties as president in July, alleging financial mismanagement of the local. She and her executive board remain suspended; however, Katz has not been officially removed from her position and is fighting the suspension.
Wilson said the e-mails could show what, if any, influence Katz had in Corzine's decision to stop the Legislature from tackling state worker pension and health care reforms in 2007.
Corzine has said no backdoor negotiations took place. Katz, however, argued that the e-mails should remain private because they involve contract talks, which are exempt from Open Public Records Act requests.
That argument infuriated CWA, which claimed in legal papers that Katz and Corzine broke the law if they engaged in collective bargaining via e-mail exchanges.