What is a shield law, exactly? When can a government official require a reporter to disclose sources or information? Who counts as a journalist under a shield law? What types of sources or information are protected? Is there a big difference between a subpoena and a search warrant?  by Jonathon Peters CJR

This is a short and useful overview of the legal basis of “privilege” and in particular how journalists’ work is covered (or not) by privilege. The situation is nuanced, as states have different precedents and there is not a single federal shield law. The use of digital communication and storing information “in the cloud” has also complicated considerations of what information must be surrendered to law enforcement by reporters, who is a reporter or journalist, and when must sources be identified.

http://www.cjr.org/united_states_project/journalists_privilege_shield_law_primer.php