So apparently Asimov’s Laws of Robotics were mentioned in Megaman 7 and X1. I don’t rmember it at the time, but now that I have been reminded, I do seem to recall that they were mentioned at some point. It’s not that important to the series, especially the X series, because basically everyone that appears is a Reploid, but I guess you never fight humans. X and the Maverick Hunters are supposed to be fighting for the humans, after all. Of course, you confront Wily at the end of every Classic game, but never kill him. They explicitly call it out in 7, and apparently in different localisations there are different outcomes.
The reason I mention it though, is I just realised the significance of a major plot point of Zero 4. Weil “reveals” at one point, very dramatically, that he is in fact a human! Aha! So there! He brings it up more than once, as I recall. However, I was very underwhelmed by this supposed revelation. Firstly, I already figured that out, but also so what? What does it matter if he’s a human—apparently Zero was led to believe he was a Reploid? So now I get that Zero must have at some point been bound by the Three Laws, and so could not harm humans.
The guy has a mostly cybernetic body anyway, but I guess that’s beside the point. And by the time of ZX the lines have been blurred so all that goes out the window. But at this time, he is banking on the fact that he can rule all Reploids because they’re not allowed to hurt him. This really could have been explained better by the game, I feel.
Zero’s response, incidentally, is along the lines of: “I don’t care if you’re human or Reploid, you are a Maverick, and so it is my duty to destroy you either way.” Like Classic Megaman in English MM7, he is now “more than a robot” and able to make his own judgements, no longer bound by the Laws. X attained this state through 30 years of rigorous morality testing, but presumably Classic MM and Zero have also achieved this level of human-like decision-making due to their life experiences (these are my own speculations). I may be misremembering some details in this post, but sometimes it’s just fun to be a fan.