(“BITs”) have recently dealt with the issue of ex post general regulations
adopted by host States that have adversely affected foreign investors. An ex post
regulation is understood here in a broad sense and comprises the following
1. Host States’ enactment of new legislation for emergency reasons, which
alters previous contractual relations with foreign investors.
2. Host States’ adoption of ex post regulations affecting foreign investors
with whom they lack a legal relationship.
3. Host States’ ex post lack of enforcement of regulations existing at the
time of the making of the investment.
4. Host States’ ex post change of the interpretation of existing regulations,
adversely affecting foreign investors.
These situations all have a common feature: the existing regulation at the time
that the foreign investors made their investment is not applied according to its
terms. The way international arbitral tribunals have resolved the disputes could
shed some light on how both States and investors could proceed before and after
the adoption of any of these forms of new regulation, despite the fact that the
controversies differ in terms of facts and underlying treaties.1
Generally speaking, the set of international awards that will be analyzed
below reveals, first, that foreign investors’ rights are preserved even in the case of
grave economic crises that force States to adopt ex post regulations affecting these
rights; second, that host States possess ample power to adopt ex post regulations