The Chilling Effect

It exists:

In fact, it’s hard to call a reporter on this beat who hasn’t felt sources withdraw as the subpoenas and seizures have piled up. “Officials are reluctant to get anywhere close to the line,” Shane said. “Take drones. The official position is that the government cannot confirm or deny the existence of a drone program in Pakistan. But the president has spoken several times, publicly, about the program. Is someone going to get into trouble for talking about it?” Few want to test the limits. “Sometimes they’ll offer some black humor about it. ‘So you want me to be the next person to go to prison?’ But it actually has been much harder to get people to talk about anything, even in a sensitive-but-unclassified area.”