북방한계선(NLL)은 남북간에 군사적 대결을 두 차례나 초래했고, 지금도 잠재적 분쟁요인으로 작용하고 있는 민감한 이슈이다. NLL문제는 영토관할권과 관련 있으며, 군사안보적인 차원에서도 매우 중요한 사안이기 때문에 법적 접근과 이해가 매우 긴요하다.
NLL은 설정목적이 정당한 것이었고 설정방법이 합리적인 것이었다. NLL은 정전협정의 미비사항인 해상 경계선을, 정전협정의 정신에 맞게 보다 구체화시킨 ‘필수적인 사후보완적 조치’라고 할 수 있다. 그에 대하여 다수 관행의 집적, 묵인, 금반언, 합의 등에 의해 이미 확고한 법제도로서 응고 내지 강화되어 왔다. 더욱이 남북기본합의서 의해 NLL의 법적 유효성은 인정되고 있으며, 금반언의 법리에 의해 북한은 이를 뒤집을 수 없다.The Northern Limit Line (hereafter abbreviated as NLL) issue still remains one of the most delicate and complicated problems in the inter-Korean relations. It has already brought sharp military conflicts in 1999 and 2002 between South and North Koreas.The purpose and method of establishing NLL by the UNC was just, reasonable and proper in terms of international law. It has become an integral part of the Korean Armistice Agreement signed in July 27, 1953. The NLL regime is now justified as valid international legal norms or principles as well as one of the widely accepted jurisprudence, such as principles of estoppel or acquiescence, pactum tacitum theory, consolidation theory etc.The 1992 Inter-Korean Basic Agreement declared and recognized the existence and effectiveness of NLL. So North Korea can not deny its legal validity. At present, the issue of establishing South-North Co-fishing Zone around NLL is under discussion between South and North Koreas. The issue is never a simple one, thus demanding systematic analysis of its legal, political, military and economic after effects.the ROK government should deal with this issue prudently, especially taking into account of the possible influence of South-North Co-fishing Zone on the NLL regime as well as on South Korean naval defence posture.