465. Expropriation as a treaty standard.

Almost all bilateral investment treaties (including UK Investment Promotion and Protection Agreements or 'IPPA's1) contain a prohibition against expropriation2. Such provisions typically prohibit expropriation or measures having effect equivalent to expropriation except where the expropriation is for a public purpose, is not discriminatory and is accompanied by prompt adequate and effective compensation3. In order for the conduct of the state to constitute an expropriation the interference with the investor's rights must be such as substantially to deprive the investor of the economic value, use or enjoyment of its investment4. The effect of the expropriatory conduct is often considered to