Defense attorneys for James Holmes subpoenaed reporter Jana Winter after she reported in July 2012 Holmes had sent his psychiatrist a notebook containing violent drawings and plans for a murderous plot.
His attorneys have not challenged the report but maintain the leak violated a court gag order. Several investigators have testified they did not give the information to Winter, and the defense attorneys have questioned their credibility.
Winter fought the subpoena in both Colorado and New York, where she works. Dori Hanswirth, her lawyer, said federal and state shield laws protects Winter's sources.
The First Judicial Department of the Appellate Division Tuesday affirmed enforcement of the subpoena, the Courthouse News Service reported.
"We note that New York's Shield Law ... continues to represent a strong public policy and the long history of vigilantly safeguarding freedom of the press," Justice Darcel Clark wrote for the court. "The dissent argues that respondent's appearance was ordered to identify law enforcement personnel, which requires the disclosure of her confidential sources. However, the facts presented on this record do not establish with absolute certainty that the Colorado District Court will require the disclosure of confidential sources."