THE CONDEMNATION of Idi Amin's bloody rule in Uganda by the 33 nations of the British Commwealth is a genuinely stirring and useful development, not to say an unprecedented one. For no condemnation has such moral effect as one delivered, in sorrow as well as anger, by the community to which the accused belongs. In this instance, the indictment is made even more weighty by the participation in it of some of Uganda's fellow black-African nations. Africans' past reluctance to criticize one of their own has seriously undermined their routine denunciations of white racism. Such denunciations, of South Africa, will henceforth have new authority.

To be sure, Idi Amin is not one to shake in his boots easily. In his buffoon's way, he had sought to humiliate the Commonwealth conference at which he was condemned by purveying rumors that he was about to attend it. Thanks to the arms and subsidies given him by the Russians and Libyans, and by his hiring of Palestinian mercenaries, he seems relatively immune to any military challenge from outside. He is almost certainly more vulnerable, however, to an eventual coup from within. "If it is known that the leaders of one billion people are morally opposed to Amin Dada," Australia's prime minister said at the Commonwealth conference, "this could contribute to the toppling of his regime." Amin is the only person ruling a country today whose removal is devoutly and publicly wished by most members of the international community.

And for good reason. Amin has authorized the murder of tens of thousands of his subjects, including many of the natural leaders and the educated classes. Personally he has engaged in cruel acts of extermination. He took one of the more promising economies in post-colonial Africa and has torn it virtually to shreds. He has become an active source of subversion and danger to other African states and a willing tool for the spread of Soviet power in Africa. He lends himself to Libya's sponsorship of international terror. Indeed, he flouts the interests and aspirations of a whole continent. His successor will be a patriot.