MADRID -- Almost two decades ago, Spanish judges led by Baltasar Garzón began an unprecedented international crusade against alleged perpetrators of human rights abuses, including former regime leaders like Augusto Pinochet of Chile.
Now, however, Spain is on the receiving end of a similar judicial move, with an Argentine judge seeking to extradite and put on trial police officials from the dictatorship of Francisco Franco who are accused of torturing regime opponents until 1975, when Franco died.
The case is being played out in Argentina's courts after a group of Spaniards claiming to have suffered such torture filed a lawsuit in Buenos Aires in 2010. They had previously failed to get redress in Spain, where such crimes are covered by a 1977 amnesty law that was designed to ease Spain's return to democracy.
However, using the same principle of universal jurisdiction for human rights that Judge Garzón had invoked in the 1990s, an Argentine judge, María Romilda Servini de Cubría, recently issued arrest warrants against four officials of the Franco regime.
Two of the men on her list are already dead, but the other two former police officers, Jesús Muñecas and Antonio González Pacheco, are expected to be summoned soon by a Spanish judge.
Even if Spain eventually refuses to extradite its citizens, the request from Argentina is in itself "a very important moral sanction on the Franco regime, which also shows Franco's victims that they can count on international support," said Victoria Sanford, professor of anthropology at City University of New York.
The Spanish government has refrained from commenting on the extradition request, pending a decision by Spain's national court. Ironically, that decision is now in the hands of Pablo Ruz, who replaced Judge Garzón three years ago after Mr. Garzón was suspended and eventually barred from Spain's judiciary for using illegal eavesdropping methods.
Mr. Garzón gained abrupt international fame in 1998 for an unsuccessful attempt to prosecute General Pinochet, the former dictator of Chile. But among his many other politically sensitive and contentious pursuits, Mr. Garzón also then tried to investigate crimes committed during the Spanish Civil War and the ensuing Franco dictatorship.
Separately, Judge Ruz is also in charge of Spain's most important political corruption case, centering on whether a former treasurer of the governing Popular Party, Luis Bárcenas, used a slush fund to make illegal payments to senior party officials, including Prime Minister Mariano Rajoy. On Monday, Judge Ruz widened that case by indicting an architect who overhauled the party's headquarters, amid suspicions that he was paid under the table for his work.
Whatever the political sensitivities in Spain, Ana Messuti, an Argentine international criminal lawyer who has been leading the Buenos Aires case against the Franco regime officials, said the recent arrest warrants should be viewed as the first rather than a final step toward bringing to account officials who violated human rights during the Franco era.
Ms. Messuti said: "We're trying to build up a mega-case that should reach a mega-result and demonstrate that Spain had a regime that carried out something akin to genocide against a whole segment of its own population."
What is seen as Argentina's meddling in Spanish affairs has ruffled feathers in Spain. It follows a legal and political standoff last year between the two governments after the administration of President Cristina Fernández de Kirchner nationalized YPF, which had been majority-owned by Repsol, Spain's biggest oil company. Repsol is claiming at least $10.5 billion in compensation from Argentina for the loss of YPF.
Furthermore, Spanish law does not foresee the extradition of its own citizens unless their citizenship has been acquired by fraudulent means, according to Javier Cremades, chairman of Cremades & Calvo-Sotelo, a Spanish law firm. Mr. Cremades said he could also not see the case progressing because "Spain's amnesty law has already resolved the legal and political issues linked to the Franco period."
But Unión Progresista de Fiscales, a left-leaning association of Spanish prosecutors, issued a statement welcoming Argentina's attempt to make amends for "the lamentable performance of our judicial system" in terms of confronting the crimes of the Franco era. "We hope the Spanish government will live up to the circumstances," it added.
Argentina's extradition request means that "we're now getting back the favor that we did to Argentina by putting an end to this notion of complete impunity," said José Galán, a Spanish lawyer.
Mr. Galán represented victims of Argentina's military dictatorship in the trial of an Argentine Navy captain, Adolfo Scilingo, whose crimes included throwing prisoners to their deaths from planes. After being indicted, Mr. Scilingo volunteered to stand trial in Madrid, but was eventually convicted in 2005 of crimes against humanity and is serving a prison sentence of 640 years.
Mr. Galán claimed Argentina's extradition request was "a real headache" for Spain's Popular Party, many of whose members are "the real heirs of Francoism." But he also noted that even under previous Socialist administrations, Spain had done little to confront its darker past and resisted calls by human rights associations and Judge Gárzon to set up an independent truth commission to investigate crimes committed under the Franco regime.
Last week, a group of victims of the Franco regime held a press conference here, in which they detailed some of the abuses that they had suffered at the hands of the officials targeted by Argentina, in particular Mr. González Pacheco, known during his time in Franco's police as "Billy the Kid" because of the way he liked to show off his gun.
Felisa Echegoyen, 65, said she was arrested in 1974 by five policemen who kicked down the door of her flat and threatened to throw her out of the window because she had helped distribute Communist pamphlets. Mr. González Pacheco, she alleged, put a kerchief in her mouth to stop her screaming and kicked her. Ms. Echegoyen said she was then beaten "almost every hour" while questioned by police at their Madrid headquarters. Eventually, she was sentenced to two years and four months, but only served part of the conviction.
Jesús Rodríguez Barrio, an economics professor, recalled how Mr. González Pacheco had pointed his gun to his head while he signed a police declaration that stated he was a Trotskyist activist.
"What is happening in Argentina is one of the last opportunities," to bring the Franco regime to justice, Mr. Rodríguez Barrio said. "We still have a generation of victims who can talk, but most of our torturers were older than us, so time is running out."
This article originally appeared in The New York Times.