The majority of countries at the Third United Nations Conference on the Law of the Sea have served notice that they will conclude a treaty governing the world's seas this year whether the United States joins with them or not. Although the significance of such a threat is difficult to assess, its potential for creating instability and hostility is considerable. In any event, it seems clear that after more than seven years of negotiation, the time has come for the US to fish or cut bait on this effort by 157 countries to replace the work of the 17th-century Dutchman, Grotius.
The historical potential of the treaty is awesome. Consider the possibility that the treaty's most unusual concept, that resources beyond the jurisdiction of any nation are ''the common heritage of mankind,'' could become in 300 years the commonplace that Grotius's ''freedom of the seas'' is today. Whether that step toward international cooperation will be taken depends in large part on US participation.
In the summer of 1980, Elliot Richardson, President Carter's representative to the Law of the Sea conference, stated that the draft treaty would probably be initialed in 1981. Last spring, however, the leaders of the US delegation to the conference were relieved of their duties the day before the conference was to reconvene and the Reagan administration announced that the treaty would be extensively reviewed because of dissatisfaction with the part of the treaty which provides for the mining of manganese nodules thousands of feet below the ocean's surface and thousands of miles from any land. The administration's unhappiness stems primarily from the fact that the principles proposed to govern the mining of this heritage do not comport with American free enterprise. The administration has now stated that it will attempt to renegotiate the provisions of the draft treaty dealing with deep seabed mining.