If you have any interest in international law at all, you should check out this post at SCOTUSBlog on the new International Court of Justice opinion in Medellin.

The truly fascinating part is how the Bush administration has repeatedly attempted to avoid having any court, SCOTUS or ICJ, decide these issues (understandibly so — the ramifications of this case are tremendous), and so has pressured Texas to halt the executions, including by direct Presidential order, yet Texas has steadfastly refused.

So we’ve got a three-way showdown. Can the ICJ trump the US Government or can the US Government avoid the question by trumping Texas? The "easy" answer is "yes" to either or both — but that will collapse either the sovereignity of the US or the sovereignity of the States or both, so the Bush Administration can’t do either.

Perhaps this conflict is why there are no historical instances of a double-layer federal/republic state-within-a-state-within-a-state.