This thesis explores the challenges posed by greater public demands placed upon transnational corporations to improve their human rights records. Its focus is placed on the oil industry because it epitomises the archetypical transnational business and raises particularly challenging human rights issues. Whereas corporations have a huge impact on the fulfilment of human rights, international human rights law is mostly addressed at states. It can be argued, though, that corporations have acquired a certain degree of international legal personality through their capacity to stand in international legal proceedings and to enter into agreements subject to international law. Contrarily to other international legal subjects, corporations have acquired international rights but not international duties. A number of mechanisms are currently under development to address this gap between legal irresponsibility and public pressure. Voluntary initiatives undertaken by companies demonstrate that the corporate discourse has evolved extremely quickly in the last few years. International lending agencies and, particularly, the World Bank Group claim to set high standards of sustainability for oil investment projects. A recent wave of transnational litigation against oil majors tries to hold them accountable at home for alleged complicity in human rights violations committed in host countries. The study of all these initiatives shows that, although these developments are scattered and uncertain, they are progressively creating a sense of obligation in human rights matters. Corporations, nowadays, cannot claim irresponsibility for human rights violations committed abroad, even if international law has not conferred human rights duties upon them. Contemporary international law has reacted to human rights violations committed by non-state actors mainly by increasing the responsibilities of the state to prevent and redress private abuses and by imposing direct obligations upon individuals in the case of the worst international crimes. While acknowledging that the current international legal system does not adequately reflect the power of private actors, this thesis will offer some proposals for translating corporate social responsibility into positive law. It will also argue that, however desirable the reform of human rights instruments may be, corporate accountability will only be made effective if the laws regulating economic activities undergo in-depth reforms.