Last February, Senate Minority Leader Robert J. Dole (R-Kan.) alarmed some of his colleagues by asserting that the Senate's view of a treaty's meaning is "legally irrelevant and in no way bind{s} the president," unless it is formally declared during the treaty's ratification.

Dole's claim, since echoed by several other Senate Republicans, suggests that vexing constitutional issues are at stake in the dispute between Secretary of State George P. Shultz and senior Democrats over procedures for Senate approval of the popular Intermediate-Range Nuclear Forces (INF) Treaty.

Leading Democrats fear that if allowed to stand unchallenged, the claims of Dole and other conservatives will amount to a unilateral surrender of Senate power to the executive branch. Last week, several Democrats threatened to delay the INF Treaty's approval unless Shultz agreed that the Senate's informal understanding of a treaty's meaning was legally binding.

But the Democrats subsequently split over whether a letter from Shultz to Senate Armed Services Committee Chairman Sam Nunn (D-Ga.) provided any assurance on this underlying constitutional point. White House spokesman Marlin Fitzwater, backed by conservative senators, insisted that Shultz had surrendered nothing of importance to Nunn.

Behind the conservatives' surprising scorn for senatorial prerogative is a desire to uphold the Reagan administration's controversial "broad" or permissive reading of the 1972 Antiballistic Missile (ABM) Treaty, which is at odds with the Senate testimony of executive branch officials at the time.

State Department legal adviser Abraham D. Sofaer, who was asked to evaluate the legal basis for this "broad" reading after the president endorsed it publicly, said last year that Senate testimony by Nixon administration officials clearly supporting a "narrow" or restrictive reading of the ABM Treaty did not bind the president because it was not mentioned in the Senate's treaty approval resolution.

In a statement that reverberated noisily through the ranks of senior Senate Democrats, Sofaer also said the treaty's meaning was determined by what U.S. and Soviet negotiators had actually agreed, "irrespective" of what the Nixon administration had told the Senate. Despite contrary testimony from all but one U.S. negotiator of the ABM Treaty, Sofaer claimed that the two sides did not agree on the "narrow interpretation."Democrats' Complaints

Nunn complained last spring that Sofaer's analysis was based on "inferential reasoning which I never was taught in law school" and amounted to an invitation for senior government officials to lie during future treaty ratification hearings. Senate Judiciary Committee Chairman Joseph R. Biden Jr. (D-Del.) said Sofaer's remark was "incredible . . . absolutely staggering." And Sen. Patrick J. Leahy (D-Vt.) told Sofaer he had allowed himself "to be a party to what I think is a charade."

But Dole, seeking to reaffirm his support for the highly realistic missile defense tests allowed by the "broad" interpretation, wrote to President Reagan that the "constitutional law is absolutely clear . . . . The final decision on interpreting the ABM Treaty is the president's alone."

Sen. Pete Wilson (R-Calif.), another proponent of missile defense tests, went so far as to state that "my beliefs at the time that I cast . . . {a treaty ratification} vote would not in any way alter . . . obligations, rights and duties" agreed between U.S. and other negotiators.

Several independent legal experts have questioned this humble view of Senate power. John Rhinelander, who was legal adviser to the ABM negotiating team, called Sofaer's claims "absolutely ridiculous as a matter of law and dumb as a matter of politics." He said the dispute, which concerns the relative position of the legislative and executive branches of government, "goes back 200 years . . . to the days of George Washington."

Laurence Tribe, a professor of constitutional law at Harvard University, told the Senate Foreign Relations Committee last year that Dole must have "misread" an authoritative legal text he cited, which states that the Senate's informal treaty views can legally bind the executive branch.Professor's Challenge

Louis Henkin, the text's principal author, writes in the current issue of Foreign Affairs magazine that the Reagan administration's reinterpretation of the ABM Treaty "to an effect different from what it had told the Senate in seeking its consent . . . would seem to be violating the constitutional conception" that the Senate's informal understanding is legally binding.

Henkin, a professor at Columbia University, challenged the administration's argument that Senate testimony supporting the "narrow" interpretation was not binding because it was not specifically embodied in the Senate's resolution approving the ABM Treaty.

"When a secretary of defense comes up with a particular meaning and the Senate seems to accept it, that's what the treaty means in the absence of clear indications" to the contrary in other executive branch testimony, Henkin said in an interview.

Both sides agree that in 1972 Senate testimony, then-Defense Secretary Melvin R. Laird and several other officials strongly backed a restrictive reading of the ABM Treaty.

Sofaer said in an interview that the gap between his position and that of his myriad critics is not as wide as "some have recently suggested." He directed a reporter's attention to remarks in one of his three reports on the ABM Treaty last year that "the record contains executive {branch} representations to the Senate which support the {narrow} . . . interpretation . . . upon which senators could justifiably have relied in granting advice and consent."

Sofaer also said he agreed with Henkin and leading Senate Democrats that "the president may well be bound {under domestic law} by executive branch statements to the Senate" about a treaty, and that this obligation outweighs any other nation's interpretation of the treaty.Drawing Distinctions

But in the case of the ABM Treaty, Sofaer insisted, executive branch assurances in 1972 were too vague to be binding on Reagan now "as a matter of law." Instead, Sofaer said he believes Reagan is free to decide the issue for himself because Nixon administration statements supporting the "narrow" interpretation were "not a significant factor in the Senate's adoption of the {ABM} Treaty."

Sofaer also drew a distinction at one point between what Reagan may be entitled to say about the "broad" interpretation and what he is entitled to do about implementing it. "The president may be bound to a {narrow} interpretation" supported by the Senate testimony of Nixon administration officials, Sofaer argued, but "it's up to him {whether} . . . to say that's a proper interpretation."

He added that it is "healthy, entirely proper, and honorable to confront the Soviets with the kind of argument {for the broad interpretation} they would put before us," even though the United States has never decided to implement the interpretation by conducting advanced space tests of missile defense technologies. At the same time, Sofaer acknowledged that the Soviets have never expressly advocated what the Reagan administration has described as the "broad" ABM interpretation.

Nunn and Senate Majority Leader Robert C. Byrd (D-W.Va.) indicated last week they believed that the dispute over these constitutional principles was largely resolved by a Shultz letter providing "important assurances . . . {about} the relationship between the Senate and the executive branch."

Shultz's letter, which was reviewed by Sofaer, pledged that the Reagan administration will adhere to the INF Treaty interpretation it is presenting to the Senate, but pointedly omitted any reference to the need for Senate approval before adopting a contrary interpretation.

Biden said this was unsatisfactory, and proposed to make Senate approval of the INF Treaty conditional on Reagan's acceptance of the constitutional principles that treaties must be carried out according to the "understanding of the text shared by the executive {branch} and the Senate at the time of ratification," and that adoption of a different interpretation would require the Senate's consent.

A Biden aide noted that this "condition" would not ruin the "broad" interpretation or affect U.S.-Soviet negotiations on the missile defense issue, because it does not address how clearly the Nixon administration's testimony supported the "narrow" ABM interpretation.

"It would instead reaffirm some important {constitutional} principles brought into question by the administration's rambunctious and wide-ranging defense of the 'broad' ABM interpretation," the aide said.

Former SALT II negotiator Paul Warnke said last week that enacting such a "condition" is not necessary. "It has always been the law that what the executive branch says to the Senate in presenting a treaty for advice and consent is legally binding," Warnke said. "Now you can say it again, but that still won't change anything and it would not prevent some subsequent group of miscreants from violating the law."

Senate Majority Whip Alan Cranston (D-Calif.) indicated yesterday that he supported Biden's "condition," however. Nunn said, "It looks as of now that some reservation may be necessary."

Henkin sees no drawback in the Senate "satisfying itself" on the underlying constitutional principle. Henkin wrote in Foreign Affairs that the Senate, lacking presidential candor on the meaning of a treaty, will be tempted to "probe ambiguities and to express {its own} understandings with nearly paranoid scrupulousness, for fear not only of what other states may make of a treaty, but of what a future executive branch will make of it."