The development of investment arbitration in contemporary international law has helped to consolidate access to justice as a principle of both customary law on the treatment of aliens and human rights law. This development has also contributed to the emancipation of individuals and private entities from the traditional institution of diplomatic protection by opening to them direct access to international dispute settlement mechanisms. At the same time, this development has raised questions whether the far-reaching penetration of foreign investment guarantees into areas of national regulation of public interest should not be counterbalanced by corresponding opportunities for access to justice and the availability of remedies for civil society in the host state. This article examines the relevant recent practice on this matter and argues that access to justice may be a unifying principle to afford protection, both at the substantive and procedural levels, to investors and peoples negatively affected by the investment, both in the territory of the host state and abroad.