Without doubt many of the executions that are carried out by China, Iran and Iraq are unfair and based upon illegal actions (under international law) by those countries. However those actions are the acts of legally empowered government and should not be subject to review by the international community. They are following the laws of their country, within the boundaries of the of countries and should not be subjected to interference from the international community.
Over time many countries has developed their way of running their country. For some one to come in and try to change that, it would be and example of over stepping their bounds, unless you knew of a better way to help the country, and had a good reason as to why you want to intervene. Now if you don't have your own country together how do you have the time to put in effort on another country?
A man was just put to death in Missouri a few days ago. Why should the West intervene when countries like the United States use the same practices. Iran, Iraq, and China are their own country and they have a right to punish their people as they see fit. You can't go after one country for doing the same thing your own country does.
No, the West should not intervene regarding executions in China, Iran, and Iraq. While Western citizens might feel dismayed or uncomfortable regarding the reasons for these executions, it is not one country's place to change laws and the justice system in another country. The West might help foreign citizens by providing assistance via international human aid organizations, by setting examples, and by providing a place of refuge for unfairly persecuted foreign citizens. However, it could be said that there is inequity in Western justice systems as well, so a better use of resources might be to improve conditions and fairness within the legal system of one's own country.