Jack Webb Spins in Grave

If I learned anything from watching old cop shows, it's this: If you know something about a crime, and you don't reveal the information to the police, you're guilty of aiding and abetting a criminal. Of course, there are ways around that. For instance, you could just blog it!

Why are journalists, and now bloggers, above the law? Shouldn't they be liable for illegal knowledge they receive from sources? What exactly are the limitations? If someone is planning, say, to assassinate the president, and gives a journalist the information beforehand without saying where or how, is the journalist required by law to reveal his identity to the police? It certainly doesn't seem like it nowadays. Anybody with a Myspace account apparently has carte blanche.