The United Nations Convention on the Law of the Sea(hereinafter referred as "the Law") adopted in 1982 was enacted on November 16, 1994. South Korea, China, and Japan signed and ratified the Law, respectively. These three countries announced their domestic laws relating to Exclusive Economic Zone(EEZ) with reserving their applications. The enactment of the Law and announcement of EEZ inevitably brought new order on the seas. The New Fishery Agreement based on the Law with EEZ was concluded between South Korea and Japan and ratified by each country′s parliament. Another New Fishery Agreement between South Korea and China is also going to be concluded in near future. The New Fishery Agreements, however, do not include regulations relating to the marine scientific research, the protection of the marine environment, and so forth, which are essential for the States to fully implement the Law According to the New Fishery Agreements, it is impossible for the Coastal States to excercise their jurisdiction. Because the agreement of delimitation ocean boundaries among the three countries are not easy to settle, provisional agreements can only be concluded. Thus, many problems including the sovereignty over Dok-do between South Korea and Japan and delimitation of EEZ between South Korea and China can be arose anytime. This paper investigates the problems and possible counter measures in legal excercise on the seas by South Korean Government. The above mentioned problems introduced by the New Fishery Agreements include potential problems in the Middle Sea Zone, Provisional Zone, and so forth. In this paper, only the legal aspect of the Zones will be discussed excluding the law enforcement and the economic aspect of the Zones.

In general, a source of international law comes out of either treaties or customs. Process of forming treaty law is relatively clear as it is created by both negotiations of legal experts in issue and express of sttes concerned in the international conferences. However, this process does not apply to the creation of customary international law. Rather the process to customary law depends on legal inference from or reasoning states' practices in fact so that there is no definite process or procedures for establishing customary international law and objective criteria to identify it. It is more difficult to prove when and what states' practices have been recognized customary law that turns to bind on all members of world community. This paper is to explore, through theories and findings of ICJ, how the customary international law is formed to be effective as a binding norm of law.