The Department of Justice seized phone records and read emails from Fox News journalist James Rosen, WaPo reports. Not only that, the DOJ alleges that Rosen committed a crime by reporting on classified information - something that reporters do every day.
Rosen reported in 2009 that the US believed North Korea would test more nuclear armaments if the UN imposed more sanctions. His source was State Department adviser Stephen Kim, and the information was classified. The FBI indicted Kim for espionage over the leak, and they are also alleging that Rosen broke the law "at the very least, either as an aider, abettor and/or co-conspirator." But publishing leaked information is not a crime, even if the information is classified.
The DOJ's surveillance of Rosen was far more extensive than their tracking of AP reporters. They tracked his movements and read all of his email correspondence with Kim, in addition to other emails.
To justify investigating Rosen, the FBI had to claim that Rosen had also committed a crime, in this case by encouraging his source to reveal classified information. But that's something journalists do constantly, as Greenwald notes. It is not only legal for journalists to publish classified information, it's also a necessary part of the way journalism acts as a check and balance on what the government does in secret. To prosecute Rosen would be "criminalizing the act of investigative journalism itself," adds Greenwald.