The future international legal status of the Caspian is surely dependent on the will of the littoral states. The way the neighbors of the Caspian water basin will decide its fate is still unknown, however from the legal point of view the theories of the classification of the Caspian will still remain debated in the doctrine.
Then most popular theory though - the one that classified the Caspian ‘sea’ as a lake - seems more valid, due to the fact that it was many times geologically proven that the Caspian is an enclosed body of water with absolutely no access to world ocean. The geological history of the Caspian being a part of larger sea thousands of years ago does not change the fact that nowadays it possesses all of the criteria of a lake. Hence, the legal status of the border lake is the most appropriate option of classification of the Caspian and should be used as the base point in the negotiations of its future international legal status. Moreover, the theory that states that Caspian ‘sea’ was historically treated as a condominium seems quite weak, due to the fact that it was never in such a legal regime de facto. Even de jure the provisions of the Russian-Iranian agreements do not hold a definite support of that theory.
Being a border lake the future international legal status of the Caspian can be determined by the examples from the state practice in that regard. Though such options are quite limited, the example of the Great Lakes and the arrangements between US and Canada seem like a good starting point. The problem is that the Caspian case is unique due to the number of parties. There is no other lake in the world that hosts five littoral states.
Another issue that would always be a tricky part of the legal arrangement is delimitation issues of the Caspian with the aim of establishing clear sovereign state borders. Not the least due to the fact that there will always be heavy geopolitical and geoeconimical factors involved in the schematics of the process.
All in all, clearly defined international legal status will be an important step in the peaceful coexistence and cooperation with the aim of sustainable development of all littoral states. The appropriate norms of the future legal status will be a determinant of the future basis of the multilateral relations regarding the Caspian and inevitably will become a unique precedent in international law and international state practice.