In late July, when the Senate Foreign Relations Committee voted to send a United Nations treaty on women's rights to the floor for consideration, its chairman, Joseph Biden, D-Del., said he supported the pact because it signaled U.S. support for women's rights and would have little consequence for Americans.

"We ought to be able to walk and chew gum at the same time," said Sen. Biden, answering charges that the United States didn't need the treaty to prove its commitment to women's rights. "This treaty will cost us nothing. We will not have to change any laws."

But will it cost us nothing? The truth is, neither Biden nor any other senator knows for sure what would happen if the U.N. Convention on Elimination of All Forms of Discrimination Against Women (CEDAW) is ratified.

The treaty, signed by President Carter in 1979 but never submitted for ratification before this year, calls on governments to abolish all legal distinctions based on sex that interfere with "human rights and fundamental freedoms." It seeks to end all discrimination against women and to modify "social and cultural patterns of conduct of men and women" to eliminate all practices based on "stereotyped roles for men and women."

Sounds OK on the surface. But the United States is hardly a serial violator of women's rights. Women here vote, hold public office and enjoy full protection against gender-based discrimination.

Yet the treaty language seems to indicate that a variety of U.S. policies may face changes if the treaty were adopted. How many? Which? No one can say for sure.

That's why, before the Senate bows to pressure to pass "something" to demonstrate willingness to engage in world institutions, Sen. Biden and his colleagues need to know what the United States would be called upon to do under the treaty. Senators need to know exactly what changes would be necessary in domestic and family law.

And that's why, since it must enforce domestic law, the Justice Department should review CEDAW and all accompanying documentation carefully. The Bush administration, which got this process rolling in March when it asked for the treaty to be ratified, has itself requested delays so it can get more information. The Senate should do the same. The idea that action must be taken by the end of this session of Congress doesn't hold water. We've waited 23 years; we can wait a few more months for this minimal effort at due diligence.

Why? Because the CEDAW committee that enforces compliance-and the non-governmental organizations, such as the aggressively pro-abortion Center for Reproductive Law and Policy, that provide "shadow reports" that form the basis of the committee's investigations-take what Ramesh Ponnuru of National Review magazine calls "an expansive view" of their mandates. The CEDAW committee has criticized Ireland, Peru, Argentina and other nations for prohibiting abortion, Belarus for establishing a Mother's Day and the Netherlands for not extending employee benefits to prostitutes. What would it criticize here?

Would the United Nations try to end Mother's Day here? Would it require us to dismantle laws requiring minors to notify adults before receiving abortions? We need to know before the treaty becomes law, and a swift, but thorough, investigation can help us.

A further complication requires a second review. The Senate may choose to add reservations to the treaty, such as the reservation added by Saudi Arabia to follow sharia-or Islamic law-regarding treatment of women when sharia conflicts with CEDAW. This, of course, renders the treaty mostly meaningless there.

Does the United Nations honor these reservations and respect the sovereignty of the countries involved? Again, we don't know. And we should, because both President Bush and President Clinton before him had reservations they wanted included should the Senate ratify the treaty. A few months of study by the Justice Department, with help from the State Department (since it reviews U.N. actions), should clear up this matter.

That's it-two relatively simple reviews. A small price to pay to ensure we know what we're getting into with CEDAW.

The Senate has the final word on this. The executive branch rendered its judgment in 1979 with President Carter's signature. If Sen. Biden is correct and the treaty will cost us nothing, fine. But on the not-inconceivable chance there are costs-costs perhaps beyond what Americans are willing to pay-we need to know that, too. Before the Senate votes.

Patrick Fagan is the William H.G. Fitzgerald fellow in family and cultural issues at The Heritage Foundation, a Washington-based public policy institute.