I was not big into crim law. But I always thought ignorance of the law wasn't a defense to breaking the law. I thought you needed intent to commit the action that is criminal, not intent to break a specific law.
Still don't understand how Clinton could explicitly intend to do a certain action, an action which happened to be criminal, but "no reasonable prosecutor" would take the case since she didn't intend to break the law (even though she intended to do the action which broke the law and there was no intent requirement in the statute).
So yes, it seems to me if Clinton was driving a car 85 in a 35, and James Comey pulled her over, if she were to say "uh well I know I was driving 85, but I wasn't driving 85 because I wanted to break the speed limit, I was driving 85 to try and avoid anyone else catching up to me", James Comey would go ahead and say, "well since you didn't intend to break the law, have a nice day."
So yes, in short, I have no idea what the difference between a strict liability crime and one that requires a culpable state of mind would be in the case of Clinton. Furthermore, I have no idea what level of intent would be read into a statute covering Clinton's conduct.
Fair enough. Ignorance of the law is (with few exceptions) never an excuse. Driving citations are almost universally strict liability - no intent required. If you are driving 80 MPH thinking you are driving 65 MPH (bad gauge, installed huge tires, whatever), it doesn't matter. You didn't intend to speed, you didn't even intend to drive 80 MPH, and it doesn't matter. Crimes almost universally require intent (which itself is almost always proven via circumstantial evidence); citations almost never do.
18 U.S.C. 798: "Whoever knowingly and willfully communicates, furnishes, transmits, or otherwise makes available to an unauthorized person" classified information has committed a felony offense. "knowingly and willingly" is the intent required. Required to do what? "communicate, furnish, transmit, or otherwise make available to an unauthorized person" classified information. Clinton knowingly and willingly intended to use a private server. Clinton did use a private server. Clinton may or may not have knowingly and willingly intended to transmit classified information through the private server, but that intent could be shown via circumstantial evidence. So let's assume she intended that (and I think that is correct). Does that mean she knowingly and willingly intended to transmit classified information to unauthorized persons (because transmitting through a private server is less secure and unauthorized (hacking, etc..))? That's a closer call, but almost certainly no (I haven't seen anyone respectable make that point). Contrast with someone like Snowden: he clearly intended to transmit classified information to unauthorized users, and he did just that.
From what I've read (caveat that I'm not some type of expert in this legal field), gross negligence is a sufficient level of intent under this statute. Gross negligence (and regular ol' negligence) is not always clear, but it's generally defined as "a conscious and voluntary disregard of the need to use reasonable care, which is likely to cause foreseeable grave injury or harm to person, property, or both. It is conduct that is extreme when compared with ordinary negligence, which is a mere failure to exercise reasonable care." Generally, when terms like this appear in a given area of law, case law slowly (and often inconsistently) reveals what specific actions are on the mens rea (state of mind) scale, from negligence to gross negligence to recklessness to willful to etc... depending on the law. So to really know the answer, you have to look at case law on the statute or analogous statutes (IIRC, not much on this particular statute, making it even grayer). To me, her conduct was somewhere in the negligence to gross negligence range. One is criminal, the other not. That's where the argument lies. The FBI Director pretty much said negligence, and that's insufficient under this law.
Final word on this: I deal with intent all the time in different areas of law, and it's a pain in the butt every time. Literally had a 6 hour meeting discussing how plaintiffs (we're representing a defendant company) could show intent (reckless, in this case). Probably a combined 50+ years practicing law in this specific area in the room and it was still almost impossible to come up with a good answer (and case law rather developed with securities laws compared to the Espionage Act). It's not easy stuff, frankly.