The Zeroth Law of Robotics was first formally laid out in Isaac Asimov's Robots and Empire (ISBN 0586062009) as an extension of his Three Laws of Robotics. It is found again in Foundation and Earth (ISBN 0553587579), in which Asimov starts the process of bringing his Robot and Foundation universes into full congruity. It is also stated, although not under the title of the Zeroth Law, in The Evitable Conflict, where it is considered a natural outgrowth of the First Law for positronic devices which have the means of large-scale extrapolation.
The Zeroth Law states:
- A robot may not injure humanity, or, through inaction, allow humanity to come to harm.
The Three Laws are then modified to explicitly forbid violation of the Zeroth Law. It is given an ordinal number of zero in keeping with lower numbered laws overruling higher numbered laws. More information can be found at Three Laws of Robotics.