Two reports on Libya are pertinent, where the West brought about regime change. One says that the oil production is recovering. This is regime change on behalf of western oil companies. This is morally unjustifiable. The other report is of chaos, and that shows the effects of regime change on a lot of innocent people in Libya. This too is morally unjustifiable. Iraq is another example. No one can credibly say that the U.S. was morally justified in causing regime change in Iraq. Afghanistan is a third case. For articles by others from other perspectives on regime change, see here and here.
It is perhaps not well understood that bringing about foreign regime change is a standard operating procedure of American governments. One can find numerous examples over the past 125 years and before that, no doubt. Recently, Ronald Reagan called for regime change in Libya. The U.S. Congress passed a law calling for regime change in Iraq. The U.S. caused regime change in South Vietnam.
There are several grounds to be opposed to U.S policies and actions that aim for regime changes. All or most all are mentioned in Ron Paul's speech against the Belarus Democracy Reauthorization Act. First, the U.S. lacks the moral authority to act for or in place of the people of a foreign land. Furthermore, we are morally culpable for the destruction of lives and property that we bring about. Second, the U.S. lacks the legal authority. Dr. Paul states "We have no constitutional authority to intervene in the wholly domestic affairs of Belarus or any other sovereign nation." Third, these interventions are usually "dangerous folly." They pragmatically weaken America in known ways. Fourth, they undermine the general welfare. They lead to adverse and destructive consequences both in the foreign country and here in America. Fifth, they typically involve the U.S. making war or engaging in acts of war or near acts of war or acts that bring on wars. What is more, most of these are undeclared wars.