When can it be called genocide?

For years, the term genocide was used to describe the ultimate crime. But that crime was rarely -- if ever -- charged, because international courts were too weak.

Now, the mechanics of international justice are modestly rising to confront the issue: for example, the International Criminal Court and the Yugoslavia and Rwanda Tribunals at The Hague.

Yet at the same time, the political sensitivity surrounding a genocide charge, which requires nations to intervene under international law, is creating friction. The cases of Rwanda, Bosnia and now Darfur demonstrate this.

Sunday, protesters in 35 nations and more than 280 U.S. cities marched against what a U.N. mission calls "apocalyptic" scenes still emerging from the Darfur war, now spreading from Sudan to Chad. Protest groups, including Amnesty International, called on Britain and the U.S. to help create a peacekeeping force.

So is Darfur a case of genocide? A U.S. Holocaust Memorial Museum committee and Colin Powell have said it is. So do at least two human-rights reports.

Yet many Sudanese experts and an International Criminal Court (ICC) don't term it genocide. They say it doesn't fit the 1948 Geneva Convention definition to win a case. This requires absolute proof of "mental intent" to kill or displace based on national, ethnic or religious identity. Hence, an ICC prosecutor this winter did not charge a Sudanese interior minister and a rebel Janjaweed militia leader with "genocide," but crimes against humanity.

The word genocide raises deep legal and moral conundrums in a globalizing world, experts say. The term has gained popular usage in a media age to describe mass atrocities, as in Darfur, Rwanda and Bosnia. Yet prosecutors and world courts are ever more cautious about leveling the charge, even when it may apply -- since it raises a requirement to intervene.

"Genocide is an explicit call to action under the 1948 treaty, a call to prevent and punish," says Diane Orentlicher at American University in Washington. Recent court rulings show that "if you wait until there is a legal certainty to prove genocide, you have waited too long," she adds.

That's where politics enter. A party or state charged with genocide will likely be isolated and stigmatized in the global community, perhaps making the situation even worse. Some Darfur activists feel Sudan hasn't been charged with genocide because that would make it impossible for governments to deal with Khartoum.

The politics of genocide rose in a ruling on Bosnia in February. The International Court of Justice (ICJ) at The Hague did not find Serbia guilty of genocide in the ethnic cleansing of Bosnian Muslims in the early 1990s. Rather, it found Serbia culpable in not preventing genocide in the Srebrenica massacre, and awarded no damages.

Early this month it came to light that ICJ judges did not read and did not seek to investigate a huge range of materials from Belgrade that were used as evidence by the U.N.-sanctioned Yugoslavia Tribunal, just down the street in this city.

New York Times reporter Marlise Simons wrote that the ICJ ruling "raised some eyebrows because aspects of Serbian military involvement are already known from records of earlier trials. ... In late 1993, for instance, more than 1,800 officers and noncommissioned men from the Yugoslav Army were serving in the Bosnian Serb Army, and were deployed, paid, promoted, or retired by Belgrade" through a secret office known as the 30th Personnel Center of the General Staff.

ICJ defenders say it is a civil not a criminal court, and that its purpose is to settle disputes between nations. Critics say the ruling seemed more about conciliation than justice.

"A lot has changed in the past 12 years; the EU is anxious to normalize relations with Serbia," says an American jurist with ties to The Hague, who requested anonymity. "I'm sure there are political pressures. The court probably didn't want to send Serbia back to the 1990s, isolate it, make it a pariah state in perpetuity. ... When it came to the legal standard required to prove genocide, the court shrank."

(Serb fugitives Radovan Karadzic and Gen. Ratko Mladic, architects of ethnic cleansing in Bosnia, still face genocide charges at the tribunal.)

U.N. High Commission on Refugees head Louise Arbour, who as prosecutor at the Yugoslav tribunal charged the former president Slobodan Milosevic with genocide, said courts should resist politics: "At the end of the day, there's going to be tension between peace and justice." Regarding Darfur, she said, "The U.N. embraced a responsibility to protect citizens from genocide."

But in Darfur, Antonio Cassese, head of the ICC investigation, "looked for three months with a large staff and could find no genocidal intent. He couldn't find a case," Arbour said.

That document, the 2005 Report of the International Commission of Inquiry on Darfur to the U.N. secretary-general, finds that the brutality in Darfur is for "purposes of counter-insurgency warfare."

Yet legal scholar Nsongurua Udombana at Central European University in Budapest, Hungary, states bluntly that the Cassesse report found no genocide in Darfur in order to avoid an obligation to act.

In a closely argued essay, "An Escape from Reason" in the spring 2006 issue of The International Lawyer, he says Darfur is far closer to genocide than the report finds.

One conundrum: "It is impossible to determine genocide while it is actually happening," Udombana says. He adds, "By not calling it a genocide, it appears to make the issue less urgent than it actually is."

He agrees with Samantha Powers, author of "The Age of Genocide," that Darfur has spawned a dynamic in which Arabs are killing Africans, and lighter-skinned and darker-skinned groups are set against each other. He says a confession by a Sudanese official isn't needed to prove genocidal intent. It can be shown via a common standard of "practice and pattern" of crime.

Marc Lavergne of the National Center for Scientific Research in Paris says prosecuting mass crimes boils down to two often different motives: an effort to change behavior, or an effort to punish. In the midst of a nightmare like Darfur, he says, a genocide charge may not be the best way to change behavior, though he admits the problem is ambiguous.

He also questions if Darfur is a genocide. The extermination is not aimed at Darfurian identity: "Darfurians who live in Khartoum are not targeted," he notes.

For years "genocide" was a sanctified word, emerging from the Holocaust, and it defined mass atrocities like the Armenian genocide, or the killing fields of Pol Pot in Cambodia. But its popular use rose in the midst of the Rwanda and Bosnia wars.

Bosnia was an early instance of systematic mass killings in close proximity to a region, Europe, with an incorporated value system based on history that contained an assumption that such crimes would "never again" take place.

Reports of mass killings along the Drina River in 1992, with Bosnian Muslim villages purged and teachers and elders shot, created a dilemma for Europe and the U.S. The State Department's initial downplaying of killings and prison camps led one midlevel U.S. diplomat, Richard Johnson, to write "The Pin-Stripe Approach to Genocide" -- an early effort to pair the term with an event that seemed to warrant it.

At the time, little notion existed of international courts as a tool to deal with mass crimes. That has changed. The Rwanda and Yugoslavia tribunals, the 1998 Treaty of Rome, the decision of the U.N. Security Council to empower indictments on Darfur by the ICC, the pressure on Serbia and Croatia to hand over war criminals -- have created pressure on regimes to change behavior, though not a preventive one.

For John Packer of Human Rights Internet in Ottawa, the world is in an "awkward moment" between the old Westphalian System of adjudication, "based on sovereign states and designed to create peace and stability between them, and a new developing model of international law."

The ICJ ruling on Bosnia "brings this awkward moment into relief," he says. "The court was caught willfully disregarding evidence showing Serbia's culpability, to avoid being put in a difficult spot."