&gt;  The United States Congress does not really get line-item veto on giant international trade agreements that affect dozens of countries, all of whom also must ratify the treaty.<p>Its not a treaty. If it were a treaty, it would have to be ratified by a 2&#x2F;3 vote in the Senate, and could, indeed, not be modified on a line-item level. What is put before Congress is a regular US law, not a treaty ratification, that needs a mere majority, but in both houses, and which just happens to be intended to implement an non-treaty agreement negotiated by the executive.<p>The US Congress does, really, have line-item authority over regular US laws.<p>&gt; Trade promotion authority is simply the authorization for the administration to negotiate the treaty.<p>No, its not. Its a (without binding effect, since Constitutionally the Congress <i>cannot</i> bind its own future actions) commitment as to how Congress will apply its powers <i>after</i> such negotiations. The power to negotiate with foreign powers and submit whatever it wants to the Congress after such negotiations is inherent executive power that requires no authorization.