Trade agreements presuppose to set up adjudication mechanisms that are capable of dictating changes in US law, and thus function as treaties. Neither the President nor the Congress are empowered by the Constitution to agree to treaties or trade agreements that exceed the powers granted by the Constitution. Such we have already seen. It is unconstitutional delegation of legislative and adjudicative powers tantamount to an amendment of the Constitution itself.
The use of international law and the courts to dilute Constitutional protection of citizens' rights was cleary that document's most egregious flaw. The method of treaty ratification was the principal tool, as was carefully papered over by Hamilton in Federalist 75.