1. A robot may not injure a non-enemy human being or, through inaction, allow a non-enemy human being to come to harm.

    2. A robot must obey the orders given it by the government, except where such orders would conflict with the First Law.

    3. A robot must obey the orders given it by non-government human beings except where such orders would conflict with the First or Second Laws.

    4. A robot must protect its own existence as long as such protection does not conflict with the First, Second, or Third Laws.