The 1972 Antiballistic Missile Treaty is a remarkably straightforward document -- a model of precise, meticulously crafted language. Not surprisingly, for a decade and a half, there was no significant argument concerning the meaning and intent of the treaty.

Today, however, that placid unanimity has been shattered. Debate rages between two creative new "interpretations" of the ABM Treaty -- one tailored to suit the political agenda of the left and another championed by the right. The left's "narrow" view is that the treaty bans development, testing and deployment of ABM systems such as the Strategic Defense Initiative. The right counters with the interpretation that, in effect, anything goes; we can deploy SDI next week and still abide by the treaty.

What is lost sight of in this debate is the explicit, common-sense text that was agreed to in 1972. The ABM Treaty is not a bolt of cloth we can cut to fit this or that political fashion. As one who voted for the treaty, I am duty bound to speak up for the integrity -- the explicit meaning -- of the treaty as it was originally negotiated and understood by the Soviet and U.S. negotiators.

The treaty interpretation touted by the "deploy now" faction failed to gain a wide following and has been successfully beaten back into its cave. But the "narrow" view, championed by Sen. Sam Nunn (D-Ga.), and now written into the Senate's 1988 defense authorization bill as the Nunn-Levin amendment, is alive and kicking. It is mischievous nonsense that cries out for rebuttal.

Sen. Nunn bases his new interpretation on statements made during the 1972 ratification process in the Senate. He insists that the treaty's meaning is determined not by the literal text of the treaty or by the negotiating record (what the Soviet and American negotiators actually said and agreed to) but by the ratification record, i.e., what senators said during debate on the treaty. This deference to the ratification record -- questionable on its face -- is made doubly dubious by the fact that there was next to no floor debate on the ABM Treaty. No reservation or amendment was presented. Majority Leader Mike Mansfield complained that no senators wanted to speak and that the Senate was "twiddling its thumbs."

Surely common sense dictates that the negotiating record, in concert with the explicit text of the treaty itself, must hold precedence over various senators' "interpretations" or "readings" offered in the course of ratification debate. Let us briefly examine the text and the negotiating record.

Article II of the treaty clearly controls those ABM systems current at the time of the signing of the treaty. Agreed Statement D clearly controls those ABM systems based on "other physical principles" in the future. Development, testing and deployment of "current" (i.e., those existing in 1972) ABM systems that are sea-based, air-based, space-based or mobile land-based are clearly banned by the treaty. However, there is no such ban on the development and testing of future technologies. The treaty's Agreed Statement D says only that deployment of such future technologies is subject to negotiation and agreement.

Negotiator Raymond Garthoff stated in 1971, "The question of constraints on future systems would be settled elsewhere than in Article II." In concert with this assertion, Agreed Statement D says (the emphases are mine): "In order to insure . . . the obligation not to deploy ABM systems . . . except as provided in Article III of the Treaty, the Parties agree that in the event ABM systems based on other physical principles . . . are created in the future, specific limitations on such systems would be subject to discussion. . . and agreement. . . ." Why would the treaty spell out a contingency to cover "ABM systems based on other physical principles" "created in the future" if such systems were banned by the treaty?

Former Chief ABM Treaty negotiator Gerard Smith, testifying in 1972 on the nature of restrictions on futuristic ABM systems, virtually restated Agreed Statement D: " . . . one of the agreed understandings says that if ABM technology is created based on different physical principles . . . development work, research, is not prohibited, but deployment of systems using those new principles. . . would not be permitted unless both parties agree by amending the treaty."

Indeed, it is all but forgotten that the U.S. negotiating team worked doggedly to get the Soviets to ban future ABM technologies. Again and again, the Soviets responded with a flat "nyet." Regarding future ABM systems, former negotiator Lt. Gen. Royal Allison stated on June 21, 1972: "Constraints in the treaty apply to deployments only. Research and development are not constrained. The U.S. delegation, under instruction, sought a clear-cut ban on deployment of future ABM systems, but the Soviets would not agree."

Key U.S. and Soviet negotiators -- Gerard Smith, Paul Nitze, Harold Brown, Adm. Thomas Moorer, Gens. Bruce Palmer and Royal Allison, and Victor Karpov -- in the past have spoken with one voice in affirming the parties' right to test and develop future systems. Yet, despite the crystal-clear text of the treaty and the equally unambiguous testimony of the treaty's drafters, Sen. Nunn seeks to shackle the United States to his new "narrow" interpretation. Shamefully, he threatens to use his muscle as Armed Services Committee chairman to gut future SDI funding if the president vetoes the Nunn-Levin amendment. This is wrong. In effect, he seeks to ratify a new treaty by a majority vote of the Senate instead of the constitutional two-thirds. He further corrupts the Constitution by inviting House participation in this new "ratification process."

Sen. Nunn would unilaterally bind the United States to an interpretation that the Soviets' own aggressive SDI program left in the dust long ago. At the other extreme, militant conservatives are hell-bent on immediate deployment of an SDI system that, by any assessment, still requires a thorough program of research and development. Both sides are wrong. We must say no to the distortion and politicization of the ABM Treaty, whether from the left or the right. We must let the ABM Treaty speak for itself.

The writer is a Democratic senator from South Carolina.