An important aspect of national sovereignty is the right to enter into international agreements and to participate in enforcing them. Being bound by agreements such as mutual-defense treaties does not weaken sovereign power. Yet some federal lawmakers have expressed concern that granting trade promotion authority (TPA) to President Bush would diminish our sovereignty - and may actually be unconstitutional.

Such concerns are misplaced. If anything, the opposite is true. With TPA, Congress agrees to take a straight up-or-down vote on trade agreements the president negotiates before June 1, 2005. It has been extended to the previous five U.S. presidents and is granted by most of our trading partners to their heads of state.

It is much more difficult for the United States to negotiate significant trade deals without an assurance that Congress will refrain from adding numerous amendments and conditions the president must take back to the negotiating table. Congress hasn't granted TPA for seven years - one reason the United States is party to only three of the 131 trade and investment agreements in force worldwide.

The TPA legislation being debated is clearly constitutional. Congress retains its authority to approve or reject all future trade agreements. It might be unconstitutional if Congress tried to delegate its authority to approve the final deal - but that's not at issue. What's at issue is whether our president will be denied an equal footing with other heads of state when he sits down to negotiate such agreements.

Congress may always kill any future agreement by withholding its final approval. The only difference under TPA is that Congress agrees not to kill the agreement by amendment (i.e., the "death by a thousand cuts"). The Constitution grants each chamber the authority to establish its own rules of procedure, and it makes sense for Congress to limit itself to straight up-and-down votes on certain resolutions, such as base closures and adjournment motions.

Some critics of TPA have pointed out that a subsequent trade deal might submit certain disputes, including labor and environmental matters, to an international body such as the World Trade Organization. This, they argue, would undermine our sovereignty.

Although we generally oppose having labor and environmental conditions in trade agreements, the TPA legislation shouldn't attempt to mandate or prohibit them outright. Some members of Congress want to require labor and environmental provisions in all future trade deals, and some want to prohibit them. The president should try to accommodate these conflicting sentiments when he negotiates future trade deals, but it raises serious constitutional questions for Congress to mandate the president's negotiating positions.

Moreover, the president shouldn't be denied the assistance of TPA to try to reconcile these conflicting congressional wishes. If he cannot negotiate agreements that satisfy a majority of both houses of Congress, nothing will have been lost in granting him enhanced negotiating authority. But no one benefits if potentially satisfactory trade negotiations are strangled in the crib.

As for the trade deals themselves, they would not be unconstitutional and they would not undermine our sovereignty if they contained an agreement to submit some disputes to an international tribunal for an initial determination. The United States will always have the ultimate say over what our domestic laws provide. No future agreement could grant an international organization the power to change our laws.

A ruling by an international tribunal that calls one of our laws into question would have no domestic effect unless Congress agrees to change the law to comply with the ruling. If Congress rejects the ruling or fails to act, other countries might impose a trade sanction or tariff, but they may do that now without any agreement or ruling.

The fact remains that no international body or foreign government may change any American laws. Congress may at any time override an entire agreement by a simple statute. In short, the U.S. Constitution - and any laws and treaties we enact in accordance with it - are the only supreme law of our land.

Although we think labor and environmental side agreements shouldn't be a part of trade and investment agreements, submitting these issues to an international tribunal for an initial ruling is no different (constitutionally) than submitting any other type of dispute to such a body.

Many important multinational agreements provide for disputes to be submitted to an international tribunal for such a ruling. Congress and past presidents have concluded that these tribunals are effective in eliminating unfair trade practices that hurt American producers and consumers.

Whether a given trade agreement should include labor or environmental provisions, or provide for disputes to be heard by an international organization is a policy question. Agreements that include such provisions are not unconstitutional and do not diminish our sovereignty. The only action that will weaken our overall sovereignty is for Congress to hobble the president's authority to negotiate trade deals with other nations by denying him enhanced trade promotion authority.

Edwin Meese III and Todd Gaziano direct the Center for Legal and Judicial Studies at the Heritage Foundation.