When independence was proclaimed and sovereignty gained, Indonesia had to enact laws to govern the seas in accordance with the geographic structure of an archipelagic state. This, however, did not mean that the country would bar international passage. The laws were necessary instruments for the unity and national resilience of the country, with a territory that embraces all the islands, the islets and the seas in between.

In view of the country's susceptibility to foreign intervention from the sea and for domestic security reasons, on December 13, 1957, the Indonesian Government issued a declaration on the territorial waters of the Republic. It stated that all the waters surrounding and between the islands in the territory came within Indonesia's sovereignty. It also determined that the country's territorial water limit was 12 miles, measured from a straight baseline drawn from the outermost points of the islands.

In the past, archipelagic states like Indonesia have unilaterally determined their 200-mile-Exclusive Economic Zones. Today such economic zones are confirmed by the International Convention on the Law of the Sea, which was ratified by the Indonesian Government on October 18. 1983, by Act No. 5 of the same year. This is the legal basis of the Indonesian-Exclusive Economic Zone.