The treaties you refer to are not self-executing. That means that the provisions of the treaties are enforced by individual nations, in accordance with their own national laws. Iran is within its rights to execute drug traffickers, despite the apparent disapproval of the Reuters writer and the clown at the U.N.
well, such a treaty as you describe would suggest a loss of sovereignty. unless I were Greece begging for money I would not picture a modern state doing that.