Interesting little note: as per some old Sup. Ct. precedent, treaties that are not self-executing do not bind the states until Congress enacts legislation to put the treaty into effect. See, e.g., Whitney v. Robertson, 124 U.S. 190, 194 (1888).
In this case, notwithstanding that the treaty in question (which I do not know the name of off the top of my head) apparently does provide that the nationals of signatories are to be provided with consular assistance, the treaty itself appears - from the reports on the need to enact legislation to review alleged violations of the treaty - to not be self-executing and thus not binding on the states until and unless Congress enacts legislation making it so.
In other words, the State of Texas appears to be at liberty to ignore the provisions of this treaty until Congress has enacted legislation saying otherwise.
That means, in essence, that Obuttocks is trying to bootstrap the binding effect of the treaty by, in essence, claiming that it ought to be binding on Texas because, if you just give Congress enough time, Congress will do what it needs to do to make the treaty binding on Texas.
Blame Bush.
No. Seriously.
Blame Bush.
Bush attempted to intervene in a similar case some years ago, and was given a 7-2 smackdown by the Supreme Court, which said in effect that the consular requirements of the Vienna Treaty could not be enforced against the States without specific legislation. That legislation never happened; Leahy is trying to make it happen now.
The SCOTUS position on this is not an old one. The Supremacy of the Constitution over Treaties has been reinforced over and over again by the Supremes. The most recent binding precedent is from 2006, I believe, but I'm not interested enough to check it. The "2006" case again reinforced Whitney v. Robertson, among others.
Bush should have simply ignored the decision of the International Court in the first place. Why he decided to open this can of worms with presidential meddling, prompting the SCOTUS rebuke, has always been somewhat of a mystery. Probably a sop to V. Fox, and the State Dept.