Read the following on the current legal thinking on signed -- but unratified -- treaties.
> Nevertheless, Article 18 of the Vienna Convention on the Law of Treaties,
> which many commentators regard as reflecting customary international
> law, provides that when a nation
signs a treaty it is obligated to refrain
> from actions that would defeat the object and purpose of the treaty until
> such time as it makes clear its intent not to become a party to the treaty.
> Some commentators further claim that this object and purpose obligation
> means that a nation that has signed a treaty is prohibited either from
> violating the treaty altogether or from violating the treaty's core or
> important provisions.
http://scholarship.law.duke.edu/cgi/viewcontent.cgi?article=2517&context=faculty_scholarship
That is a legal "loopholus intrepretus" which this particular DOJ could/would drive a truck through.