Brief history of the Espionage Act (18 USC 793, et seq) ...
http://www.spartacus.schoolnet.co.uk/FWWespionage.htm
Publisher of an anti-draft pamphlet was jailed, and the conviction was upheld in Schenck v. United States, 249 U.S. 47 (1919).
Rosenberg isn't a good example for this case. They were accused, convicted and sentenced for passing information surreptitiously. Hansen would be a more apt corrolary to Rosenberg.
Ellsberg and The Pentagon Papers is a decent starting point too.
No, I know thanks. I just like reminding them of the death penalty for traitors