1982年海洋法公約之締結可說是沿岸國與海洋國之間在各自的海權主張與國家利益相互妥協之下所達成的國際協議。具體制度上，除了專屬經濟區之外，另一個可以體現此種妥協結果的產物即爲群島國制度。有關群島概念的法律討論，與海域劃界有緊密的關係，因爲在島嶼林立的國家，海域劃界的理論與實踐將影響沿岸國的生存與發展的利益。在群島國制度與群島原則的理論發展與法制化過程中，菲律賓與印尼均扮演相當重要之角色。藉由國家主張、國際司法裁判以及國家實踐，使得直線基線，乃至於群島基線成爲擁有特殊海岸地形之國家劃定其領海的依據。群島國適用群島基線，該基線內部之群島水域成爲既非內水，亦非領海的獨特海洋空間，其雖屬群島國家之主權範圍，但其他國家亦可在遵守海洋法公約相關規定之前提下享有特定權利。本文從海洋法公約之立法過程中，探討國家實踐與國家主張對於群島國制度的影響，特別是在六○年代新興國家紛紛獨立之後，強化沿岸國陣營在國際外交會議上的影響力，也間接促成群島國制度能在第三次海洋法會議初期，即已確立制度上的初步輪廓。最後，從已確立之直線基線原則與群島原則之觀點，檢視中華民國領海基線所可能存在之問題點。

The United Nations Convention on the Law of the Sea (UNCLOS), concluded in 1982, is a compromising international agreement between coastal states and maritime states, considering their own claims of sea power and national interests respectively. Besides the exclusive economic zone, the emergence of the regime of archipelagic States also reflects the result of such a compromise. The legal issues of the concept of archipelagic states are closely related with the maritime delimitation, the theory and practice of which deeply influence the existence and development of an archipelagic or coastal state. In the theory and the legalization of the regime of archipelagic states and the archipelagic principles, both the Philippines and Indonesia play an important role. This paper discusses the effect of those state practices and national claims upon the regime of archipelagic states. After the 1960s, new independent states help coastal states to strengthen their diplomatic influence in international conferences, which in turns causes the regime of archipelagic states to be established roughly in the early stage of the third United Nations Conference on the Law of the Sea (UNCLOS Ⅲ). Meanwhile, this paper aims to examine the possible problems of the baselines drawn by the Republic of China from the point of view of established straight-baseline principles and archipelagic principles.