MADRID — Spanish judges have earned a reputation as superheroes of international justice, using Spain's provision of "universal jurisdiction" to go after the villains of the world.

But their crusading spirit has generated diplomatic anger and Spanish lawmakers are now moving to put a lid on it.

The drama has played out repeatedly in Spain's Audiencia Nacional, or National Court.

Victims of Argentina's Dirty War found no recourse at home when their first democratic government passed the Ley de Punto Final, a law that granted impunity to those responsible for systematic rape, torture and murder during the country's military dictatorship.

Spain's National Court came to the rescue.

The court handles cases of terrorism, organized crime, drug trafficking and serious financial crimes pertaining to Spain. But it also has 16 international cases open, involving countries from Rwanda to China to Guatemala to the United States. Some of these cases have no connection to Spain.

While they are a small fraction of those underway in the court, the headlines these cases make and the waves they cause with some foreign governments have some referring to Spain's National Court as the Universal Court.

The philosophy underpinning universal jurisdiction is that there are crimes so hideous — such as genocide and torture — that they cannot go unpunished, and so must be tried, somewhere.

Supporters agree that ideally the country where the crimes were committed would conduct the trials. If the country doesn't want to move forward, or if it can't, there is recourse in the International Criminal Court. The trouble is this court has limitations. It can only try cases that happened after 2002. Cases can only be initiated by prosecutors — not victims, advocacy groups or citizens as is permitted in Spain. And some countries like China and the United States have not signed or ratified the International Criminal Court Statute.

This is where universal jurisdiction comes into play, allowing a third country to dictate justice for those crimes.

"Massive violation of fundamental rights is a matter of international law. No nation can say it is an internal issue," said Francisco Jimenez, professor of international public law at King Juan Carlos University.

Critics see universal jurisdiction as a violation of a country's sovereignty, charging that it is up to a country's own courts to decide whether or not to try alleged criminals.

Several recent controversial cases have aided attempts to limit the law in Spain, one of 15 countries to have exercised the principle of universal jurisdiction since World War II, according to Amnesty International.

One judge, Fernando Andreu, decided to accept a complaint against Israeli military officials for the killing of several civilians in Gaza in 2002. This angered the Israeli government and the Spanish media reported that Spain's minister of foreign affairs, Miguel Angel Moratinos, promised then-Israeli foreign minister, Tzipi Livni, to change the legislation.

Another judge, Santiago Pedraz, is investigating the killings of Tibetans in March 2008. The press agency Servimedia reported that an unnamed representative from the Chinese Embassy in Madrid warned that Pedraz will be arrested if he travels to China and "will get what he deserves."

The court is also considering moving forward with a case against six former Bush administration officials for designing the legal coverage to justify torture at Guantanamo. A political adviser from the U.S. Embassy in Madrid, William Duncan, met with national court's chief prosecutor, Javier Zaragoza  in the National Court, the Spanish media reported. The U.S. Embassy said its officers hold meetings with courts on a regular basis, as part of diplomatic business, but it could not confirm this meeting.

"The courts and only the courts will make a decision," said Spain's vice president, Maria Teresa Fernandez de la Vega. But Spain's attorney general, Candido Conde-Pumpido, said he would not support the case, as did Zaragoza.

"We cannot become the world's judicial gendarmes" or be "in daily diplomatic conflicts," said Carlos Divar, president of Spain's Supreme Court, quoted in the Spanish media.

The likely reform — probable since Spain's two major political parties are in agreement — would not put an end to universal jurisdiction, but it would establish limits. It would likely require a Spanish connection in the case, in the form of Spanish victims or the presence of the accused in Spain, and that the case is not already being investigated in the country where the crimes were committed or by the International Criminal Court.

Spanish legislators approved a proposal to amend the current law because it is a "risk to national interests" and due to the "inefficiency of sentences" in some cases. Parliament still needs to vote on the amendment and it remains to be seen whether it would be applied retroactively to cases that are already open.

Supporters of absolute universal jurisdiction are adamant. "Norms cannot be changed for political interests. It's a shame," said Antonio Segura, a lawyer with more than 10 years of experience in universal jurisdiction cases. "Judges are demonstrating they are braver than politicians," he said.

The Argentines who resorted to Spain's National Court saw justice done, at least in part: Adolfo Scilingo, a former Argentine military official, was sentenced to prison.

No such luck though for Chileans when Spanish Judge Baltasar Garzon requested the extradition of former Chilean dictator Augusto Pinochet, who was seeking medical treatment in the U.K. Authorities eventually denied the request, citing Pinochet's poor health, and sent him back to Chile.

Indeed, most cases have not ended up in a trial. Spanish law does not allow for judges to try cases unless the defendants are present, and foreign governments are often uncooperative in extraditing their nationals.

No superhero is without an Achilles heel.