In interpreting one of the most contested investment treaty protection standards – fair and equitable treatment – arbitral tribunals have increasingly referred to the necessity for an investor to conduct a due diligence investigation before investing in a host state. Foreign investors have been required to assess not only commercial, but also general socio-political risks. The investor’s due diligence in the context of the fair and equitable treatment standard (FET) goes beyond the risk-based business due diligence performed by a foreign investor for its own benefit. It has implications for a state’s right to regulate in the public interest and also contributes to a broader notion of business responsibilities. This post elaborates on this issue.