Abstract: The framework on which the U.N. Arms Trade Treaty (ATT), currently being negotiated, is likely to be based is clear: It will set out criteria that signatories must apply to proposed arms transfers and require them to decide whether the proposed transfer poses a risk under any of those criteria. But these criteria are likely to be ill-defined, and the ATT's "checklist" model differs fundamentally from the "guidance" model that the U.S. currently employs. Worst of all, the ATT will enumerate criteria that will be easy to expand in ways that the U.S.