He had initially been adopted as a prisoner of conscience in 1962, when he was sentenced to five years in jail for inciting a strike of African workers.[13] This was reversed after the Rivonia Trial showed that Mandela now had turned to violently opposing the South African regime. The reversal evolved in 1964 into a worldwide debate and a poll among the members of Amnesty International. The overwhelming majority decided to maintain the basic rule, that prisoners of conscience are those who have not used or advocated violence.[14]