Law Zero: A robot may not injure humanity, or, through inaction, allow humanity to come to harm. Law One: A robot may not injure a humanbeing or through inaction allow a human being to come to harm.
Law Two: A robot must obey the orders given it by human beings, except where such orders would conflict with the First Law.
Law Three: A robot must protect its own existence, as long as such protection does not conflict with the First or Second Laws