Regional and inter-regional investment treaty-making involving more than two parties can take different forms (notably, negotiations within a regional grouping, negotiations between a regional bloc and a third country, or negotiations between like-minded countries) and can bring challenges and opportunities.

The current approach to regionalism leads to a multiplication of treaty layers, making the network of international obligations even more complex and prone to overlap and inconsistency.

However, regionalism can also provide an opportunity for rationalization of the IIA regime. If parties to nine current regional negotiations (i.e. those where BITs-type provisions are on the agenda) opted to replace their respective BITs with an investment chapter in the regional agreement, this would consolidate today’s global BIT network by more than 270 BITs, or close to ten per cent.