'This decision re-affirms the principle of universal jurisdiction, contributing to efforts all over the world to bring to justice those responsible for serious human rights violations,' Amnesty International said.

Ricardo Miguel Cavallo (also known as Miguel Angel Cavallo), was assigned to the notorious Naval Mechanics School (Escuela de Mecanica de la Armada, ESMA) in Buenos Aires, Argentina, where many of the victims of the military junta that ruled the country from 1976 to 1983 were taken and last seen.

Cavallo was arrested by Interpol-Mexico on 24 August 2000 on suspicion of involvement with the illegal importation of used cars. Immediately following his detention, the Spanish authorities sought his extradition to Spain for alleged crimes of genocide , terrorism and torture Amnesty laws passed in 1986 and 1987 in Argentina protected those implicated in human rights violations from prosecution in Argentina.

On 12 January 2001, a court in Mexico ruled that there were grounds for complying with Spain's extradition request regarding the allegations of genocide and terrorism, but not of torture. On 2 February 2001 the Mexican Foreign Ministry ratified the legal ruling and made the important point of including torture. Cavallo's lawyer is to lodge an appeal (amparo).

Cavallo is the second former member of the Argentine military to be detained abroad for human rights crimes during the 'Dirty War'. The first, Jorge Olivera, detained in Rome last year, was later released. Cavallo is one of more than 90 former members of the Argentinian security forces under investigation by Baltasar Garzon, the same Spanish judge who sought the extradition from the United Kingdom of Augusto Pinochet in 1998.