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

Zeroth law
In 1985 he postulating a "zeroth" law

• A robot may not injure humanity, or, through inaction, allow humanity to come to harm.