The rule of exhaustion of local remedies is a general one well established in international law.1
Primarily, it ensures the possibility for the State whose responsibility is involved to correct if necessary the alleged violation within its own legal framework. It is in particular relevant in cases of diplomatic protection. The rule is enshrined in article 295 of the Convention:
Exhaustion of Local Remedies
Any dispute between States Parties concerning the interpretation or application of this Convention may be submitted to the procedures provided for in this section only after local remedies have been exhausted where this is required by international law.