My view of having a mens rea requirement with child porn statues are derided with comments like:
"Congratulations, you're now on an FBI watch list." ( (s)he did agree with me)
Yet if there is no guilty mind, there should be no crime. Frankly possession of CP shouldn't be a crime at all, because it is proof of a crime. Snuff videos aren't illegal. Rape videos (of 18+) aren't illegal. Just horrible videos are that: horrible. They aren't illegal.
And that's not to go after the idea of "I plant CP on your machines..." Strict liability means you lose.