Does a 9-year old possess the aforesaid requirements? In short, I don't know, but the reason why I don't completely reject the possibility of them having the capacity to consent to sex is due to the fact that some people hit puberty when they are 9, which means they can certainly possess a sex drive, but determining whether or not they can fully comprehend or understand sex or information about it would require inductive evidence through the aforesaid methods (sex ed tests, body language and communication lucidity observations etc), preferably done by a unbiased psychologist. I'm being objective/scientific with this thought process and this actually isn't my personal view or opinion on it. If you want that, I would definitely bet against them being able to, but I haven't seen any damning evidence against it at this time unless the person is pre-pubescent. Why do I get the feeling that you have no interest in being objective about this and that a certain retard named Finian (who doesn't comprehend anything about this issue and continuously asserts non-sequiturs and other logical fallacies while seeming to think that he is intelligent) gave you the idea to ask me this? Anyway, here's my honest answer. If you want my complete view on this entire issue read my past posts on it. You should also read Larken Rose's steemit and facebook posts about this if you want to see someone who isn't an emotional child speak about this issue. By the way, teach Finian basic logic for me, will you? ;)