Judith Miller, the ex NYT reporter who was jailed for contempt of court for refusing to name sources in the Valerie Plame affair, wrote an Op-Ed piece in the Wall St Journal, advocating a federal shield law that would allow "reporters" to keep their confidential sources confidential.
Current federal law gives no special rights or privileges to reporters. They are just plain ordinary citizens in the eyes of the federal law. When a judge demands a citizen testify in court, he can compel testimony with the threat of a contempt charge. Contempt is a crime that carries a jail sentence, and the judge can impose same purely on his say-so, no jury, no appeals. The only exceptions are clergymen do not have to reveal things learned in confession, lawyers do not have to testify against their clients, doctors do not have to testify against their patients, wives do not have to testify against husbands (and vice versa), and the citizen does not have to testify against himself (5th Amendment).
These exceptions have been part of common law since Blackstone's time (or before) . The law allows one to keep intimate conversations with very close relatives and advisers secret. The protection against self incrimination is an American innovation to prevent extraction of confessions by cruel and unusual methods.
Problems arise with a shield law. Who's a reporter anyhow? With the rise of blogs just about anyone (like me) can claim to be a journalist. I would resent a law that gave privileges to NYT reporters that were denied to me. If a broad definition of journalist is used, then nearly anyone in the country can refuse to testify on the grounds that they are journalists.
Then I have reservations about "confidential sources" in the news business. A news story based upon confidential sources is most likely a smear. Ask John McCain about that. Or the confidential source fears prosecution for compromising classified information. CIA officers leaked highly classified information about tapping bin Laden's satellite phone, reading electronic financial transactions, tapping Al Quada cell phones, and wire tapping international calls. All of these leaks did grave damage to US intelligence. Far as I am concerned, those sources ought to be revealed and then prosecuted for espionage against the United States.
So, no shield law. If the judge says "testify", you testify or go to jail.