I made no suggestion that the U.S. was not in violation of the Vienna Convention. The failure to provide consular access was a violation of Article 36.part of our obligation was to establish domestic laws that would take care of those details. Obviously we didn't establish those laws, so the way I see it we violated the treaty right there. How am I mistaken?
However, as the Convention did not provide self-executing language and Congress had not adopted laws setting forth specific consequences of a failure to provide consular access, the Supreme Court was left to determine whether the defendant had received due process. It could not reasonably have been expected to legislate where Congress had not done so, much less, develop specific legal remedies for a Convention that contained none with respect to the relevant issue.
The defendant received due process. As due process had been provided, the procedural defect did not rise to the level that required that the verdict reached on the substantive evidence of the case to be overturned.
The ICJ had no jurisdiction to require otherwise. Its latest criticism of the U.S. also has no substantive impact.
As I support Article 36 of the Vienna Convention, I very much hope that the current Congress will adopt appropriate legislation that creates a reasonable framework for addressing similar issues should they arise in the future. Otherwise, decisions in such cases will need to be judged strictly by whether they meet the legal standards as defined in the U.S. Constitution and its laws. The same would, of course, apply to any other sovereign state. The test would be whether the legal process met their own legal standards.
In the end, I believe treaties and agreements need a level of concreteness to address failures with respect to treaty/agreement obligations. As the Vienna Convention contained no such concreteness, the responsibility for the outcome rests not with the U.S. Supreme Court--it made the only decision it could given the facts of the case and circumstances associated with the Vienna Convention--but with the Vienna Convention's absence of a reasonable remedy for the situation that occurred.