The United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances of 1988 is one of three major drug control treaties currently in force. It provides additional legal mechanisms for enforcing the 1961 Single Convention on Narcotic Drugs and the 1971 Convention on Psychotropic Substances. The Convention entered into force on November 11, 1990. As of January 1, 2012, there were 185 Parties to the Convention.[2] These include 182 out of 192 United Nations member states not Equatorial Guinea, Kiribati, Nauru, Palau, Papua New Guinea, Solomon Islands, Somalia, South Sudan, Timor-Leste and Tuvalu, and the European Union and the Cook Islands.
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.