Abstract
In determining the content of the FET standard, the tribunals stated protection of investor's legitimate expectations, due process and denial of justice, transparency, discrimination and arbitrariness, good faith, etc. The most major elements of the FET standard is the protection of the investor's legitimate and reasonable expectations. It is necessary to consider whether it is possible to what the expectations of investors are protected as legitimate and it is formed under any circumstances. If host state frustrate investor's legitimate expectations, it found a breach of the FET. The host state's specific assurance may reinforce investor's expectations, but such explicit statement is not always necessary. The host state must preserve a stable environment for investments. However, It must not be understood as the inalterability of the host state's legal framework. It implies that the host state's subsequent changes should be made consistently and predictably. The host state is entitled to exercise a reasonable regulatory authority to respond to changing circumstances in the public purpose. Therefore, whether the violation FET shall be determined through a balanced against the investor's legitimate expectations and the host state's reasonable regulatory exercise in the public interest. And investor should keep in mind that the principle of proportionality is applied unless host state provides stabilization clause or similar commitments to investor. Also host state should establish the basis of an argument about reasonable regulatory authority for public interest.
