And just as an addition, the three laws of robotics are not the nice little taglines given in the trailer.
The three laws of Robotics:
1) A robot may not injure a human being or, through inaction, allow a human being to come to harm
2) A robot must obey orders given to it by human beings except where such orders would conflict with the First Law.
3) A robot must protect its own existence as long as such protection does not conflict with the First or Second Law.