Some history on the "Treaty" clause of the Constitution...

[kentuck]

http://en.wikipedia.org/wiki/Article_Two_of_the_United_States_Constitution#Treaties

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The President may enter the United States into treaties, but they are not effective until ratified by a two-thirds vote in the Senate.[9] In Article II however, the Constitution is not very explicit about the termination of treaties. The first abrogation of a treaty occurred in 1798, when Congress passed a law terminating a 1778 Treaty of Alliance with France.[10] In the nineteenth century, several Presidents terminated treaties after Congress passed resolutions requesting the same.[11] In 1854, however, President Franklin Pierce terminated a treaty with Denmark with the consent of the Senate alone. A Senate committee ruled that it was correct procedure for the President to terminate treaties after being authorized by the Senate alone, and not the entire Congress. President Pierce's successors, however, returned to the former procedure of obtaining authorization from both Houses. Some Presidents have claimed to themselves the exclusive power of terminating treaties. Abraham Lincoln, for instance, terminated a treaty without prior Congressional authorization, but Congress retroactively approved his decision at a later point. The first unambiguous case of a President terminating a treaty without authorization, granted prior to or after the termination, occurred when Jimmy Carter terminated a treaty with the Republic of China.[12] For the first time, judicial determination was sought, but the effort proved futile: the Supreme Court could not find a majority agreeing on any particular principle, and therefore instructed the trial court to dismiss the case.