Law of the Sea's tempest-tossed negotiator

The United Nations Law of the Sea Conference, which began its 86th week of negotiations on March 8, is now in the final countdown. It is directed to complete a treaty designed to prevent anarchy and chaos in three-fifths of the Earth's surface by April 30. It would welcome help from any quarter to calm the seas roiled by the Reagan administration and bring this essential treaty safely to port.

Some 150 nations waited from March 2, 1981, to Jan. 29, 1982, for the Reagan decision to return to the negotiations. During this time, ideological foes of international institutions, proponents of laissez-faire economics, and mining companies seeking more favorable terms battled it out with strong treaty supporters, particularly in the Defense, State, and Transportation Departments. Their final gasp produced the long-awaited ''book'' of specific United States amendments on the fifth of the scant 21 allotted negotiating days. US amendments concentrate solely on the system of mining the seabed beyond national jurisdiction which permits mining by corporations and by an ''enterprise'' managed by treaty signatories. Credit for this tardy achievement must be given to a dedicated US team which worked bleary-eyed for three nights while a tempest raged around Ambassador James L. Malone and his key aide Leigh Ratiner.

Mr. Malone, once a lobbyist for Taiwanese and Japanese power companies, did not appear for the conference opening. The Washington Post had announced that morning that Malone was being relieved of his position as assistant secretary of state for oceans and international environmental and scientific affairs where controversy swirled about his nuclear sales abroad. There followed three days of public controversy over the respective status and suitability of Malone; one of his deputies at the State Department, Harry Marshall; and Ratiner.

Mr. Ratiner, a Washington attorney, is a well-informed former US seabed mining negotiator and former lobbyist for Kennecott Copper, a firm interested in seabed mining. Despite his credibility-damaging zigzag career and often Byzantine negotiating style, Ratiner now appears to represent the best hope of obtaining a treaty which includes the US.

On March 10, the New York Times reported that the State Department's contract office denied having approved Ratiner's nearly $100,000 policy review fee for services between Oct. 1 and Feb. 23. It further reported criticism by Sen. Alan Cranston of possible conflict of interest between clients of Ratiner's law firm (Dickstein, Shapiro and Morin) and the Law of the Sea. While Ratiner's denials seem not devoid of credibility, the March 11 Times reported that he was taking a leave of absence from his law firm to enter the government payroll during this conference session as a deputy to Malone.

A clique of right-wing foes of the treaty, who had lost when the President decided to return to the conference with a mandate to negotiate, appeared to be the major source of these attacks. Their efforts were compounded by liberal opponents of nuclear sales and skeptics of the past record of both Ratiner and Malone as special-interest lobbyists.

Delegates accustomed to delegation heads from foreign ministries raised diplomatic eyebrows over this ragged performance. They longed for the pre-Reagan days when competent US ambassadors afforded leadership befitting the world's greatest maritime power, whose overall strategic, environmental, resource, and world-order interests are adequately served by this treaty. In fact, the US is the world's No. 1 beneficiary.

Whatever the background of Ratiner, he is an experienced negotiator and an advocate of ''flexible response'' who nevertheless recognizes that certain changes in the treaty are required to make the mining system fly both with industry and the US Senate. He needs his chance. Given the President's mandate to return to the negotiations to seek an acceptable treaty, one must wonder whether this constant hectoring from Washington is not calculated to stay any chance of achieving such a treaty.

Should the administration lay no steady hand on this tiller, or even should Ratiner shake off his impediments and develop more credibility and finesse, the conference has its work cut out for it. Once again, in order to refashion the almost successful compromises of 1980, a handful of moderate diplomats must bring resources from within themselves: from their own mastery of the complexities, from their seasoning in this seemingly impossible consensus process, and from their own inner grace. Led by conference president T. T. B. Koh and Group of 77 chairman Alvaro de Soto, they must find what is acceptable in the US amendment book.

Even if they are unable to satisfy the US, modest changes may bring Western Europe and Japan into the treaty. This could make future US adherence to the treaty more likely, since otherwise there could be no seabed mining industry under the US flag in compliance with international law, only under the flag of a country signing the treaty.