The U.S. Senate responded decisively today to Secretary of State John Kerry’s recent signature on the U.N. Arms Trade Treaty (ATT). In a bipartisan letter led by Senators Jerry Moran (R–KS) and Joe Manchin (D–WV), half of the Senate has officially pledged to oppose the ratification of the ATT. The signatories include every Republican Senator except Mark Kirk (R–IL) and five Democratic Senators. The letter, with its 50 signatories, ends any prospect in the foreseeable future of Senate ratification of the ATT.

The signatories base their opposition to the treaty on six points, including the Administration’s decision to violate its own red line by backing the adoption of the treaty through a majority-rule vote in the U.N. General Assembly. They also note that, because ATT contains “only a weak non-binding reference to the lawful ownership and use of, and trade in firearms, and recognizes none of these activities, much less individual self-defense, as fundamental individual rights,” it could pose a threat to rights protected under the Second Amendment.

The signatories are also concerned about the vague standards at the heart of the treaty, which they fear will “steadily subject the U.S. to the influence of internationally-defined norms.” They therefore oppose all treaties that “allow foreign sources of authority to impose judgment or control upon the U.S.” With this letter, half of the Senate has therefore rejected the left’s strategy of using transnational norms to remake the United States and its constitutional order. This rejection will be important in future Senate debates and public consideration of all treaties and other international commitments.

While the Senate has the lead responsibility for treaties, the House must pass any implementing legislation that is necessary to bring a treaty into effect. Because it has the power of the purse, it is also particularly responsible for funding the implementation of the ATT. A bipartisan letter, paralleling the one in the Senate and led by Representatives Mike Kelly (R–PA) and Collin Peterson (D–MN), has been signed by 181 Members—more than 40 percent of the House.

These letters are a milestone in the congressional rejection of the ATT, and the public owes a debt of gratitude to the leaders of these letters. But as vital as these letters are, they are not the end of the story. The State Department accepts under the customary international law of treaties that the U.S. is bound not to violate the “object and purpose” of a signed but unratified treaty. Both Senate and House letters reject this assertion.

The Administration has also implied that it can implement the ATT through its existing authorities and without new appropriations. It is therefore incumbent on the Senate and House to reject this claim (as both the Senate and the House have already done through previous actions), hold appropriate hearings on the treaty and the Administration’s proposed implementation of it, and prepare the way for this President or a future one to “unsign” the ATT and thereby end this dangerous and senseless experiment with a U.N. treaty and its vague standards.