The extent of a nation's power over its coastal ecosystems and the natural resources in its coastal waters has been defined by two international law doctrines: freedom of the seas and adjacent state sovereignty. Until the mid-twentieth century, most nations favored application of broad open-seas freedoms and limited sovereign rights over coastal waters. A nation had the right to include within its territorial dominion only a very narrow band of coastal waters, within which it had the authority but not the responsibility, to regulate all activities. But, because this area of territorial dominion was so limited, most nations did not establish rules for management or protection of their territorial waters. Regardless of whether or not nations enforced regulations in their territorial waters, large ocean areas remained free of controls or restrictions. The citizens of all nations had the right to use these unrestricted ocean areas for any innocent purpose, including navigation and fishing. Except for controls over its own citizens, no nation had the responsibility, let alone the unilateral authority, to control such activities in international waters. And, since there were few standards of conduct that applied on the "open seas", there were few jurisdictional conflicts between nations. The lack of standards is traceable to popular perceptions held before the middle of this century. By and large, marine pollution was not perceived as a significant problem, in part because the adverse effect of coastal activities on ocean ecosystems was not widely recognized, and pollution caused by human activities was generally believed to be limited to that caused by navigation. Moreover, the freedom to fish, or overfish, was an essential element of the traditional legal doctrine of freedom of the seas that no maritime country wished to see limited. And finally, the technology that later allowed exploitation of other ocean resources, such as oil, did not yet exist. To date, controlling pollution and regulating ocean resources have still not been comprehensively addressed by law, but international law – established through the customs and practices of nations – does not preclude such efforts. And two recent developments may actually lead to future international rules providing for ecosystem management. First, the establishment of extensive fishery zones extending territorial authority as far as 200 miles out from a country's coast, has provided the opportunity for nations individually to manage larger ecosystems. This opportunity, combined with national self-interest in maintaining fish populations, could lead nations to reevaluate policies for management of their fisheries and to address the problem of pollution in territorial waters. Second, the international community is beginning to understand the importance of preserving the resources and ecology of international waters and to show signs of accepting responsibility for doing so. As an international consensus regarding the need for comprehensive management of ocean resources develops, it will become more likely that international standards and policies for broader regulation of human activities that affect ocean ecosystems will be adopted and implemented.