So holds a Second Circuit panel in New York Times v. Gonzales, over a dissent. I think the majority is right, though I'd have a quibble or two here or there. Here's the panel's summary:
After the attacks on the World Trade Center and the Pentagon on September 11, 2001, the federal government launched or intensified investigations into the funding of terrorist activities by organizations raising money in the United States. In the course of those investigations, the government developed a plan to freeze the assets and/or search the premises of two foundations. Two New York Times reporters learned of these plans, and, on the eve of each of the government's actions, called each foundation for comment on the upcoming government freeze and/or searches.
The government, believing that the reporters' calls endangered the agents executing the searches and alerted the targets, allowing them to take steps mitigating the effect of the freeze and searches, began a grand jury investigation into the disclosure of its plans regarding the foundations. It sought the cooperation of the Times and its reporters, including access to the Times' phone records. Cooperation was refused, and the government threatened to obtain the phone records from third party providers of phone services. The Times then brought the present action seeking a declaratory judgment that phone records of its reporters in the hands of third party telephone providers are shielded from a grand jury subpoena by reporter's privileges protecting the identity of confidential sources arising out of both the common law and the First Amendment....
We hold first that whatever rights a newspaper or reporter has to refuse disclosure in response to a subpoena extends to the newspaper's or reporter's telephone records in the possession of a third party provider. We next hold that we need not decide whether a common law privilege exists because any such privilege would be overcome as a matter of law on the present facts. Given that holding, we also hold that no First Amendment protection is available to the Times on these facts in light of the Supreme Court's decision in Branzburg v. Hayes, 408 U.S. 665 (1972).