> How did this manage to survive first amendment challenges?
This goes back to what Phil Zimmerman said about ITAR and such almost 20 years ago when they threw it at him for PGP:
"The Government has made it illegal in many cases to export good cryptographic technology, and that may include PGP. This is determined by volatile State Department policies, not fixed laws."
This has nothing to do with law and everything to do with those same volatile policies a generation later.
ITAR, like all US federal regulations codified in the CFR, have the full force and effect of the law. See the first couple paragraphs here for further explanation:
http://library.law.unh.edu/AdminLaw
How do you know if something is subject to ITAR? The State Department has a big list. It's called the US Munitions List (USML). At the time Zimmerman said that, PGP probably wasn't on the list. But I assure you, blueprints of guns are absolutely on the list.
What's really funny is that 2d blueprints of the m16 and others exist and are readily accessible. Also, the army has published in the past various handbooks for insurrection. The "improvised munitions handbook" comes to mind.
This goes back to what Phil Zimmerman said about ITAR and such almost 20 years ago when they threw it at him for PGP:
"The Government has made it illegal in many cases to export good cryptographic technology, and that may include PGP. This is determined by volatile State Department policies, not fixed laws."
This has nothing to do with law and everything to do with those same volatile policies a generation later.