The three laws of robotics

1. First Law : a robot may not injure a human being or, through inaction, allow a human being to come to harm
2. Second Law : a robot must obey the orders given it by human being except where such orders would conflict with the First law.
3. Third law : a robot must protect its own existence as long as such protection does not conflict with the First or Second law.

(Isaac Asimov)