The Helsinki Memorandum of Understanding (MoU) signed in 2005 and facilitated by Finlandformer President Martii Ahtisaari with support from the European Union has brought peace toAceh after 30 years armed conflict between the Government of Indonesia and the Free AcehMovement. The EU involves both in short and long term monitoring programs. During the missionin Aceh, several serious incidents involving the use of light weapons and directed toward the EUpeace mission were recorded. Indonesian domestic law acknowledges the protection must be deliveredto the Internationally protected person based on Vienna Convention 1961 on Diplomatic Protectionand other related conventions. Would the ratification of Vienna Convention satisfy the protection forthe EU peace mission? An Act on Foreign Relation enacted as legal basis for International relationincluding with the EU and its missions argue would be able to answer the question. On the other side,EU enacted Protocol on the Privileges and Immunities of the European Union (the Protocol) tosecure its mission overseas. The protocol is a specific legal instrument within the EU legal regimethat was enacted to fulfill the needs of an International legal instrument on EU's legal personalityparticularly the privileges and immunities aspects. The Protocol answers a main concern on legalrelation between a State and EU mission including EU peace missions. However, as a non-memberState and as a matter of law, Indonesia does not ratify the Protocol consequently Indonesia doesnot bind with the Protocol. The Indonesia Act on Foreign Relation is considered very basic for thecurrent condition. Consequently, different interpretation between related State organs occurred. Asa result, ineffective protection for the protected person such mandated by the International lawremain measured. This condition does not suppose to happen since although remain debatable,an International cooperation, an influential external power nowadays is playing very importantrole including in a peace process. Moreover, as Indonesia is strengthening its position within theinternational community, some improvements crucial to be supported.