The New York Times is weighing whether to appeal a decision of the judges who ride the Second United States Circuit that opens the way for a federal prosecutor to get a look at records of the newspaper’s phone calls. We genuinely wish them luck. We don’t have a great deal of regard for the way the Times has handled these sourcing fights; it agitated for pressing the Valerie Plame investigation only to find its own reporter in prison for refusing to provide evidence. But we do have a great deal of regard for the rider of the Second Circuit, Judge Robert Sack, who has dissented in the latest case. This case, about possible calls to two Islamic charities under investigation, is different from the Valerie Plame matter. But it involves the same prosecutor, Patrick Fitzgerald, and the same reporter, Judith Miller. If the Times does appeal, the document to focus on is Judge Sack’s dissent, in which a liberal judge has laid down some markers that conservatives can appreciate.

Judge Sack was, before being elevated to the appeals bench, one of the great press lawyers of his time. He was general counsel to Dow Jones & Company, where he came to be revered by its reporters for his idealism and wisdom and his fidelity to the First Amendment. He is the author of the legal classic, “Libel, Slander and Related Problems.” In his dissent in the latest case, Judge Sack emphasizes that the majority of the three judges on the panel acknowledge that a First Amendment privilege may exist for reporters and, in what we thought was a shrewd piece of legal craft, whittles the issue down to the question of who gets to decide whether the prosecutor has met the burden needed to pierce that privilege. Is it the prosecutor himself or the court? Judge Sack does not feel that in this case the prosecutor has met the burden and, in any event, doesn’t feel the prosecutor should be treated by a court with such deference that the prosecutor becomes the one to decide whether the prosecutor has met that burden.

Judge Sack noted that the Second Circuit panel did confirm, at least in principle, the ability of journalists to protect the identity of their sources in the hands of third-party communications-service providers: “Without such protection, prosecutors, limited only by their own self-restraint, could obtain records that identify journalists’ confidential sources in gross and virtually at will. Reporters might find themselves, as a matter of practical necessity, contacting sources the way I understand drug dealers to reach theirs — by use of clandestine cell phones and meetings in darkened doorways. Ordinary use of the telephone could become a threat to journalist and source alike. It is difficult to see in whose best interests such a regime would operate.”

The real question he sees is “not so much whether there is protection for the identity of reporters’ sources, or even what that protection is, but which branch of government decides whether, when, and how any such protection is overcome.” Framing this as a kind of mini-separation-of-powers, checks-and-balances issue strikes us as a good starting point for courts working their way through this constitutional minefield. There has been much talk about abuses by the press in recent years, but experience has taught us to worry far more about abuses by prosecutors. Judge Sack has sketched it in a sage way. In the end we predict that the legacy of Mr. Fitzgerald will be to have underscored that whatever branch of the government is given authority to pierce any reporters’ privilege, it would not be wise for it to be the prosecutor.