The US Supreme Court is expected to hand down its judgement in Kiobel v Royal Dutch Petroleum in the first half of 2013 in which it will decide on the legitimacy of recent human rights claims against Western companies under the US Alien Tort Statute 1789. In so far as these claims have unsettled accepted wisdom on the horizontal application of human rights law to companies and their extraterritorial enforcement by US courts, the decision is anticipated - with some trepidation - by human rights activists, businesses, governments, academics and last but not least the victims of the corporate human rights abuses in the third world. This paper explores the legitimacy of the horizontal application of human rights to companies generally and, more specifically, in circumstances when such application is endorsed in respect of individuals (see e.g. Nuremberg trials and international criminal tribunals). The discussion will test the reasoning of the courts in Kiobel and similar litigation concerning the accountability of private actors under public international law (including their understanding of ‘public’ role of the abusive agent) against more general theories of human rights accountability and corporate agency.