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Unfavorable court rulings have the news media facing their most serious challenge in more than three decades over protecting the identities of confidential sources.

The latest defeat came last week when a federal appeals court in Washington declined to reconsider a three-judge panel's ruling compelling Time magazine's Matthew Cooper and The New York Times' Judith Miller to testify before a federal grand jury about their sources or go to jail for up to 18 months.

The two reporters have been called to testify about the leak of an undercover CIA's (search) officer's name.

In a separate case, The Associated Press and other news organizations are appealing a federal judge's decision finding five reporters in contempt for refusing to identify their sources for stories about nuclear scientist Wen Ho Lee (search). Appeals court arguments are scheduled for May 9.

The judge says the information from the reporters is needed so that Lee, who was wrongly suspected of spying, can pursue his privacy lawsuit against government officials.

Last year, Providence, R.I., TV reporter Jim Taricani was sentenced to home confinement after he refused a court order to reveal the confidential source of an undercover FBI videotape of an alleged bribe. He served four months.

The New York Times and Time are hoping the Supreme Court (search) will intervene and use the case of Miller and Cooper to clarify the law.

Different courts have ruled in different ways on the issue of reporters and their sources and this is "an ideal time for the Supreme Court to take this case," said Bruce W. Sanford, a partner with the Washington office of Baker & Hostetler who has represented the press on many issues.

Other experts on the issue of press freedom and the law doubt the high court will accept the case. They say the circumstances in the current leak investigation appear to parallel a landmark case in which the court dealt the media a major setback.

"There's no particular indication that the court is looking to revisit this area of the law," Georgetown University law professor Richard Lazarus said.

In the 1972 Branzburg v. Hayes (search) decision, the court ruled 5-4 that a Louisville (Ky.) Courier-Journal reporter had to tell a grand jury the identity of his sources for stories on drug trafficking.

Journalists pressed state legislatures to enact "shield laws" that handed reporters what the Supreme Court would not — the right to guard the identity of their sources, a vital tool in investigative reporting. Many states did.

However, Congress has not passed a similar law to apply to reporters in federal probes. A bill is pending but it's unclear whether it has enough support to pass.

Experts say that in many ways lawyers representing the news media have done a remarkable job over the last three decades turning an essentially adverse ruling in Branzburg to their advantage, arguing with success in many instances that the news media does have a privilege to protect sources.

The media's lawyers relied on language in Branzburg by then-Justice Lewis Powell (search), who wrote a separate concurring opinion that was somewhat sympathetic to the press.

"It was a classic case of making lemonade out of lemons, and to a large extent it worked; the problem is, now the courts aren't buying it anymore," said Jane Kirtley, a professor of media ethics and the law at the University of Minnesota.

A 2003 case in federal appeals court in Chicago was seen as a turning point, with a three-judge panel concluding, "We do not see why there need to be special criteria merely because the possessor of the documents or other evidence sought is a journalist."

The case involved three Chicago newspaper reporters who turned over to an Irish court taped interviews with an FBI informant.

Twenty-six media organizations including the AP filed court papers calling the ruling a stunning break from longstanding precedent.