Discussions at the “Freedom of Investment” Roundtables, hosted by the OECD Investment Committee, have stressed that increased investments by foreign State-controlled investors can bring significant benefits to home and host societies, but have also noted that they can raise concerns. This paper examines two principal issues concerning foreign State-controlled investors: whether the doctrine of foreign state immunity may make it difficult for private parties to pursue legitimate claims against them and whether that doctrine creates regulatory enforcement gaps for host countries. Although the restrictive approach to immunity is now widely recognised, important issues, such as whether the financial investment activities of a sovereign wealth fund are commercial or sovereign acts, remain uncertain. In the area of regulation, the paper analyses state policies in the area of tax, competition law and criminal law, and notes key factors that may influence immunity in such cases.