The project finance industry has been growing at an increasingly rapid rate during the past few years, due to the efficiency with which large scale construction projects can be funded using this method. Growth within this area has been concentrated particularly within developing products such as India and China where project finance has facilitated the construction of new cities and infrastructure. 1 Relatively little research has concentrated on the role of project finance in the West, even though the US and the UK remain important sources of project finance. The aim of this essay is to analyse the system of investor protection legislation which exists within the UK and the USA, with a particular focus on the extent to which the systems of legislation which prevail in both countries is effective in protecting investors from the threat of expropriation. The essay will conduct a detailed comparison between the two systems of legislation. In order to achieve this aim, the essay will conduct a detailed discussion of the different systems of project finance legislation in both the UK and the US, which will be followed by an evaluation of the level of investor protection which is offered in both countries, and an analysis of the extent to which such legislation has been effective at providing protection from expropriation. This will be conducted by an analysis of both domestic and international law, and relevant case law.The results of the essay find that there are significant areas of ambiguity in both UK and US law concerning investor protectionin the UK, this is due to the fact that there is a considerable overlap between the contents of different bilateral investment treaties, UK domestic law, and the provisions of European Union treaties. Research also suggests that there are areas in which both UK and US law on investor protection deviates from international law, such that it is unclear what circumstances constitute expropriation.