> Before any international agreement may be ratified, [our country] must pass all the laws needed to comply with that agreement ahead of time, through regular democratic processes.
In the US it must go through the Senate, the President, and depending on things the House may have some say in the funding:
> Treaty power is a coordinated effort between the Executive branch and the Senate. The President may form and negotiate, but the treaty must be advised and consented to by a two-thirds vote in the Senate. Only after the Senate approves the treaty can the President ratify it. Once it is ratified, it becomes binding on all the states under the Supremacy Clause. While the House of Representatives does not vote on it at all, the supermajority requirement for the Senate's advice and consent to ratification makes it considerably more difficult to rally enough political support for international treaties. Also, if implementation of the treaty requires the expenditure of funds, the House of Representatives may be able to block or at least impede such implementation by refusing to vote for the appropriation of the necessary funds.
That's the problem - everything gets packaged into one treaty, under one vote, with a lot of political momentum behind it. Like hiding objectionable laws in 9000 page budget bills.
But you raise a good point - without a single-subject rule [1], we would be quickly back to square one, as instead of voting on ratification, there would be a large "Trans Pacific Partnership Omnibus Bill" that would simply have everything thrown in, without giving the public or the system the chance to examine each clause individually.
In the US it must go through the Senate, the President, and depending on things the House may have some say in the funding:
> Treaty power is a coordinated effort between the Executive branch and the Senate. The President may form and negotiate, but the treaty must be advised and consented to by a two-thirds vote in the Senate. Only after the Senate approves the treaty can the President ratify it. Once it is ratified, it becomes binding on all the states under the Supremacy Clause. While the House of Representatives does not vote on it at all, the supermajority requirement for the Senate's advice and consent to ratification makes it considerably more difficult to rally enough political support for international treaties. Also, if implementation of the treaty requires the expenditure of funds, the House of Representatives may be able to block or at least impede such implementation by refusing to vote for the appropriation of the necessary funds.
https://en.wikipedia.org/wiki/Ratification#United_States