No one more stridently denounces South Africa's violations of human rights than Ghana's Kwame Nkrumah. Last week he dispatched a recorded diatribe to an anti-apartheid rally in London, whose participants protested the law under which South African citizens may be jailed for interminably repeated 90-day stretches. The very next day Nkrumah armed himself with a measure that makes the South African statute look pale by comparison.
Since 1958 Nkrumah has wielded a law allowing his government to lock up any Ghanaian without trial for five years, merely by charging that the activities of the accused might prejudice national defense, relations with...