Dr Reza Ghaffari, who is on a speaking tour of Ireland as a guest of Amnesty International, began his career of political activism with a demonstration against Richard Nixon.
This was not in the 1970s on some comfortably radical American campus but in the Tehran of 1953, when Nixon was Eisenhower's vice-president and Dr Ghaffari a high school student of 16. His actions earned him six months' detention in a military barracks and expulsion from the Iranian education system.
In 1962 he left for the US, where he gained a primary degree, a masters and then doctorate in political economy. In 1973, during a "liberal" phase of the Shah's regime, he returned to teach at the University of Tehran. In the late 1970s, as a member of Fadi, a leftwing group inspired by the Cuban revolution, he was involved in political agitation against the Shah.
The turn which the Iranian revolution took after 1979, however, was to place him - and tens of thousands of others - in even greater danger than he had under the Shah's autocratic and often brutal regime. The ruling clerical faction led by Ayatollah Khomeini set about destroying all elements of the secular opposition. They came for Dr Ghaffari one bright summer dawn in 1983.
In captivity he was moved from prison to prison and tortured repeatedly. He suffered a stroke and lapsed into unconsciousness. "The stroke," he says, "may have saved my life since I was from then on physically incapable of telling them anything."
In Evin prison the governor, Haji Lajevardi, "the Eichmann of Evin", would visit the cells and offer detainees the choice of being in a firing squad party - and living - or joining the lists of those to be shot. In 1988, Amnesty estimates, 4,000 to 5,000 prisoners were murdered in Iranian jails.
Given a conditional release in 1990, Dr Ghaffari left Iran two years later. Dr Reza Ghaffari will be speaking tonight in Cork and tomorrow, International Human Rights Day, in Dublin. Details from Amnesty: phone 01 6776361