NEW YORK, Sept 22 (Reuters) - A state appellate court on Thursday ordered a hearing to determine whether a doctor in a defamation suit can require a hospital to provide her with computer data it says it already deleted.

Tribly Tener, an obstetrician-gynecologist who works at hospitals in New York and New Jersey, served New York University with a subpoena requesting the identity of everyone who accessed the Internet on April 12, 2009, through a portal at NYU's Bellevue Medical Center. The subpoena was part of Tener's effort to track down the person who posted defamatory remarks about her on Vitals.com, a website where people can review medical professionals.

Tener believed that the post she alleged defamed her was written from a computer connected to NYU's network.

When NYU, which is not a party to the defamation suit, failed to produce the information, Tener filed a motion for contempt which was denied by Justice Doris Ling-Cohan, of state Supreme Court in Manhattan.

In a case of first impression, the Appellate Division, First Department, unanimously reversed Ling-Cohan's ruling and sent the matter back to the Supreme Court for a cost-benefit analysis. Among the factors the lower court must consider, the court said, are whether there is software that can retrieve the data; whether that data will actually identify who used the Internet from that location and accessed Vitals.com; and an estimated budget for the retrieval.

"That NYU is a nonparty should also figure into the equation," the ruling said. "Of course in the event the data is retrievable without undue burden or cost, the court should give NYU a reasonable time to comply with the subpoena."

CONSIDERING BURDEN ON NONPARTY

The anonymous post on Vitals.com cast doubt on Tener's skills as a doctor and urged potential patients to stay away from her, according to the defamation suit she filed in July 2010.

In her defense, Tener argued that she was board-certified and had never been sanctioned or suspended from practice.

NYU insisted thousands of people could have accessed a site through its network. While computers which access the web through that network appear in a text file, the file is automatically overwritten every 30 days and the facility does not have the technological capability or software to retrieve them, according to the hospital's argument cited in the decision.

Tener submitted an affidavit from an expert contending that it is still possible to retrieve the data. The court ruled the issue warranted further review.

"NYU offered no evidence that it made any effort at all to access the data, apparently because it believed it could not, as a nonparty, be required to install forensic software on its system," Justice Karla Moskowitz wrote for the court.

The court held that Tener had demonstrated "good cause" to require the performance of the cost-benefit analysis.

"Plaintiff's only chance to confirm the identity of the person who allegedly defamed her may lie with NYU," the court said.

The case is unusual in that the court is considering making the same discovery demands of a nonparty that it would of a litigant, said Samuel Santo Jr., former chairman of the E-Discovery Task Force at Lowenstein Sandler.

The court is "trying to balance the plaintiff's need for this information versus the burden imposed upon a nonparty to retrieve and produce that information," he said.

Lawyers for NYU declined to comment. Tener's lawyer Steven Wagner applauded the ruling, which he said "gives guidance to attorneys in these types of difficult cases in the future."

The case is Tribly Tener M.D. v. Miriam Cremer et al, Appellate Division of the Supreme Court of New York, No. 5059.

For Tener: Steven Wagner, Bonnie Berkow and John Overland of Wagner Davis.

For NYU: William Cusack and Ricki Roer of Wilson, Elser, Moskowitz, Edelman & Dicker.

(Reporting by Jennifer Golson)

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(A previous version of this story did not identify the appellate court that issued the ruling. It is the Appellate Division, First Department.)