The recent moderate trend to increasingly apply human rights law in investment awards is accompanied by certain new investment treaties which include expressed human rights provisions. An analysis of recent investment awards indicates that though there are some ‘winds of change’ in this field, it is equally noticeable that human rights law is far from being mainstreamed in international investment law. Investment arbitration procedural law is also undergoing a process of change, and the new procedural rules tend to enhance public elements in the investment arbitral system. This study is aimed at explaining these recent legal changes, highlighting the role of social movements in reframing investment relations as well as increasing public pressure to apply human rights law. These framing changes concern broadening the frame of investment arbitration (beyond the foreign investor–host state dyad), reversing the perceived balance of power between investors and host states, and zooming-in on local individuals and communities residing in host states. The discussion on factors impeding legal change in this field emphasizes the role of the private legal culture prevalent in the investment arbitration system, which is reflected and reinforced by certain resilient socio-legal frames. Informed by this analysis, the study suggests some legal mechanisms which can mitigate the inter-partes frame, and increase the application of human rights law in investment arbitration; inter alia, rigorous transparency rules that are likely to facilitate increased public pressure on tribunals and increase the participation of social movements representing local actors in arbitral processes.