America's allies may ruefully discover one day that their mutual security treaties with the United States are worth the paper they are written on - but little more.

This holds true of our agreements with NATO and SEATO partners, the cornerstones of free-world defense in Europe and the Pacific. The same would be true of any defense treaty offered to Israel as a means of encouraging a Middle East peace settlement with the Arabs. And the loophole has cropped up in the dispute over the Panama Canal treaties.

Since our emergence as a global power following World War II, the United States has signed eight mutual security treaties involving 42 partners. On the surface, they appear to require our government to respond militarily without hesitation should armed aggression be committed against, say, West Germany or Australia.

This simply isn't the way it would work. In the thicket of language in every treaty is an escape cause - a clear proviso that the United States reserves to itself the right to determine in its own self-interest what military action, if any, would be taken should a treaty partner be attacked. Not one treaty to which we are a party, in short, pledges the automatic introduction of American troops into hostilities, no matter how close or vital the ally is.

This facet of U.S. foreign policy was directly addressed last July by the Senate Foreign Relations Committee at hearings to review the operations and effectiveness of the War Powers Resolution of 1973. In a preparatory memorandum, the committee's legal counsel, Michael Glennon, posed this question: "Does any treaty to which the United States is a party authorize the President to introduce the Armed Forces into hostilities or require the United States to do so, automatically, if another party to any such treaty is attacked."

Glennon gave this unequivocal reply: "The answer to the question posed is no, for two reasons at the wording of the treaties and their legislative histories make clear that they were not intended to be so construed, and be such a construction would be constitutionally dubious."

In his analysis, Glennon found that every treaty "provides that it will be carried out by the United States in accordance with its "constitutional process" or it contains other language to make clear that the United States' commitment is a qualified one - that the distribution of power within the United States government is precisely what it would be in the absence of the treaty, and that the United States reserves the right to determine for itself what military action if any, is appropriate."

Moreover, wrote Glennon, "because the Constitution vests the power to declare war in the Congress rather than the Senate, a strong argument can be made . . . that approval for United States entry into war must involve the House of Representatives . . . " And it is doubtful whether the decision to declare war can "constitutionally be delegated to the President, whether by treaty or by law."

Does this render a pledge of assistance from the United States worthless? What, exactly, is the value of a U.S. defense treaty? Concluded Glennon:

"United States mutual security treaties represent affirmations of a general intent to render assistance in good faith to another party if that party is attacked. However, no treaty to which the United States is a party authorizes the President to introduce the Armed Forces into hostilities or requires the United States to do so, automatically, if another party is attacked."

Other constitutional-law experts have oncurred with Glennon's opinion. "The treaty power," according to Raoul Berger, "cannot be construed to deprive the House of its right to participate in a declaration of war or an authorization of hostilities."

Scrutiny of the records reveals that not even America's closest European allies have been given any unconditional guarantees.

Allies who are contemplating treaty arrangements with the United States, some experts believe, would be well-served to keep the principle in mind. The Carter administration, for example, has begun to float the idea that the United States might be willing to sign a bilateral defense treaty with Israel if the Israelis will agree to a peace settlement with the Arabs. But, said one congressional authority, Israel would be "deluding itself" if it thought a defense treaty constituted an iron-clad guarantee of American assistance in time of war.

The nation of Panama, as well, should understand that the proposed U.S.-Panama "neutrality" treaty does not dicate an automatic response from the United States in time of trouble. Indeed, American negotiators inadvertently omitted an escape clause when they drafted the treaty. Under pressure from the Senate Foreign Relations Committee, however, the error was corrected in the joint communique between President Carter and Gen. Omar Torrijos.