Did Fast & Furious violate the Arms Export Control Act?
First, the Arms Export Control Act, 22 USC §2778.. It authorizes the President to define defense articles and regulate their export. In so doing, he must consider the possibility that export could "support international terrorism, increase the possibility of outbreak or escalation of conflict..."
Those defense articles may not be exported without a permit, issued by the Secretary of State ( Department of State guidelines here), "except that no license shall be required for exports or imports made by or for an agency of the United States Government
(A) for official use by a department or agency of the United States Government, or
(B) for carrying out any foreign assistance or sales program authorized by law and subject to the control of the President by other means."
The firearms involved here were not being exported for official use by an agency, nor as part of foreign aid. This a lot narrower than the GCA exception for acts by a government agency, and for good reason: the purpose of this statute is to control executive agency actions. No gun running to foreign governments or persons without a paper trail (and in cases of large transactions, a prior request for Congressional approval).
Any person who willfully violates these provisions "shall upon conviction be fined for each violation not more than $1,000,000 or imprisoned not more than ten years, or both."
There have been some reports of agents having directly transferred firearms to drug cartel buyers, in order to boost their "street creds." That'd clearly be a violation. In other situations, the person who actually exported the firearms would be in clear violation. But what of those government supervisors who allowed the arms to flow -- especially the cases where a protesting FFL was told to sell the guns anyway?
18 U.S. Code §2 provides:
"§ 2. Principals
(a) Whoever commits an offense against the United States or aids, abets, counsels, commands, induces or procures its commission, is punishable as a principal.
(b) Whoever willfully causes an act to be done which if directly performed by him or another would be an offense against the United States, is punishable as a principal."