WASHINGTON, July 4 — When the TransAfrica Forum decided to speak out last month against Zimbabwe's president, Robert Mugabe, for condoning the jailing, beating and killing of black opposition party supporters, it shouldn't have been all that surprising. After all, for decades, TransAfrica, a research and lobbying group based here, has been speaking out on the struggles of Africans on the continent and elsewhere. In the 1980's, for instance, it led the anti-apartheid marches that helped press the American government to change its policy of "constructive engagement" with the white government of South Africa. In the 90's the group protested...