What I want to know is if this could be considered willful negligence. In the past (i.e. before ~WW2) knowledge about the harmful effects of some types of radia

What I want to know is if this could be considered willful negligence. In the past (i.e. before ~WW2) knowledge about the harmful effects of some types of radiation was not "common knowledge, even among otherwise educated people. After the bomb (esp. after the Crossroads Baker and Castle Bravo test that introduced a lot of the world to the term "fallout") and the changes seen in medicine (x=ray, cancer treatments, fears about cancer in general) I would guess that most of the population is at least aware that ionizing radiation can be dangerous, even if they do not understand the specifics. Radiophobia and the anti-nuclear movements have certainly amplified the fears about anything involving "radiation". The fact that "radiation" means "always very dangerous" to many people is evidence of this attitude. So I suggest that trying to claim ignorance about the potential dangers of pointing an active x-ray emitter at someone should be handled the same way as we treat claims of being ignorant about guns. For most cases, claiming "I didn't know that guns were dangerous" is going to be dismissed as an obvious lie or gross negligence. Is there any reason a jury should treat "I didn't know that using an x-ray beam was dangerous" as a valid get-out-of-jail explanation? Note: I understand that low-level operators may not have been told how the machine works (such things would be for a court to decide). Responsibility flows upwards, and if it was a commercial product, some Professional should have had to sign off on the design. In any case, someone had to authorize these scanners... which I call mens rea. [edit] A valid defense, of course, would be to have the results of some very rigorous safety analysis that showed there was no danger. Preferably by a 3rd party. If this study existed, I suspect it would have already been shown to the public.