THE HAGUE The collapse of the International Criminal Court's case against an ally of Kenya's president-elect Uhuru Kenyatta is the latest blow to a tribunal under close scrutiny for securing just one conviction since it was set up more than a decade ago.
Handed the difficult - some might say impossible - task of building cases for crimes committed years earlier and many thousands of miles away, based on testimony from often unreliable or uncooperative witnesses in hostile environments, prosecutors have struggled to make charges stick.
The unraveling of the case against Francis Muthaura is illustrative of the court's difficulties.
Muthaura was accused, along with Kenyatta, of crimes against humanity for allegedly orchestrating violence after Kenya's 2007 election that cost 1,200 lives. Both men deny the charges.
Chief Prosecutor Fatou Bensouda concluded last week it was impossible to pursue the case against Muthaura. A key witness had recanted, other potential witnesses had been killed or were too afraid to testify and the government was not cooperating, she said. "In the circumstances, we do not feel we have a reasonable prospect of conviction," Bensouda reasoned.
Lawyers for Kenyatta, who won the presidential election earlier this month, have asked for the charges against him to be withdrawn in view of the Muthaura case.
Legal experts say prosecutors need to reconsider their methods in light of the setbacks. They point to persistent problems with witness selection and witness reliability.
Last December, Congolese fighter Mathieu Ngudjolo Chui was acquitted of war crimes and crimes against humanity at the end of a three-year trial during which the testimony of witness after witness was found to be unreliable.
Problems with witnesses were also cited in the cases of Callixte Mbarushimana, whom prosecutors accused of leading a rebel group that carried out rapes and killings in Congo in 2009, and Bahar Idriss Abu Garda, a leader of an anti-Sudanese force in Darfur accused of leading attacks on U.N. peacekeepers.
The court dismissed the charges against Mbarushimana in 2011 saying there was insufficient evidence to proceed. Judges refused to confirm charges against Abu Garda in 2010, also for lack of evidence. Both men deny the charges.
"It's pretty bad when, as in the Ngudjolo case, judges don't believe the witnesses," said William Schabas, an international law expert at Britain's Middlesex University.
The prosecutor's office, which is appealing the Ngudjolo acquittal, said in a written response that criticizing the court on the basis of its track record was wrong.
The court was being held to the highest standard of justice in the world, it said. The system was working, it added, though that might not be obvious to all observers, especially those who had hoped for more.
"In the decades and centuries to come, there will be more convictions and more acquittals. This is how fair justice works, and it is how it should work."
BIG POWERS DID NOT SIGN UP
The ICC was seen as a successor to the Nuremberg tribunals that tried Nazi war criminals and U.N.-backed ad hoc courts such as the International Criminal Tribunal for the former Yugoslavia (ICTY), also based in The Hague, and the tribunal that sought those responsible for massacres in Rwanda.
The world's first permanent international criminal court, it was set up under the Rome Statute in 2002 to pursue justice for victims of war crimes and crimes against humanity in places where courts are weak. It has the support of most of Africa, Latin America and Europe, but not the backing of big powers the United States, China, Russia and India.
The court can only investigate crimes in countries which are signatories to the Rome Statute or when the U.N. Security Council asks the ICC to become involved, as it did in the case of Muammar Gaddafi's violent crackdown on pro-democracy protesters in Libya.
It is hemmed in by the fact that investigators can only operate on sufferance of the countries they are working in, which can complicate the situation in dangerous or hostile areas. With no police force of its own, it relies on their cooperation to make arrests too.
Securing reliable witnesses under these circumstances - the key issue - is very difficult, said Stephen Rapp, the U.S. ambassador responsible for international criminal justice, who prosecuted former Liberian president Charles Taylor in the Special Court for Sierra Leone and was previously a prosecutor in the United States.
The burden of evidence in these cases was huge, he said.
"And that's not easy in areas where witnesses need to be convinced to give evidence, where you need to move them to safety," he told Reuters.
Rapp does not see the task as hopeless, however. He is encouraged, for example, by President Barack Obama's decision to expand an existing bounty program to allow the United States to pay rewards for information that helps bring ICC suspects to The Hague.
Of the court's $130 million a year, $28 million goes to the prosecutor's office, with a staff of 217 legal professionals. Judges salaries and other salary costs account for much of the budget, according to the ICC's website.
Luis Moreno Ocampo, an Argentine who made his name with successful prosecutions of members of Argentina's military juntas in the 1980s, was the ICC's first chief prosecutor. Bensouda, a Gambian lawyer, was his deputy.
The only conviction the ICC has secured to date is Congolese warlord Thomas Lubanga. In contrast the ICTY convicted 68 of the 101 suspects it took to trial. Of the Rwanda tribunal's 75 completed cases, only 12 have so far ended in acquittals.
Moreover all of the court's cases so far have been in Africa, which has created a credibility gap on that continent where many see it as innately biased, a suggestion the court rejects. It has opened preliminary examinations outside sub-Saharan Africa, including in Libya, Afghanistan and Colombia.
The court has managed to curb the freedom of those it indicts. Although Sudan's President Omar Hassan al-Bashir has travelled widely since he was indicted, including a state visit to China, he has been discouraged from attending a number of international gatherings.
Bosco Ntaganda, a fugitive Congolese warlord, surrendered at the U.S. embassy in Rwanda on Monday and asked to be transferred to the ICC, where he faces war crimes charges.
Still, the court has not lived up to the highest expectations.
SAFETY, COOPERATION BIGGEST CONCERNS
Former prosecutors, attorneys and legal experts interviewed for this story said dangerous conditions for investigators and lack of cooperation were the most problematic constraints.
Previous one-issue tribunals may have had an easier job because hostilities were easing or had ended, some said.
Nick Kaufman, a former prosecutor at the ICTY and the Special Court for Sierra Leone who now defends suspects at the ICC, said investigations for the Yugoslav tribunal were helped by the fact that NATO peacekeeping forces were often close by.
"The ICC is often dealing with ongoing conflicts in difficult and dangerous working environments," he said.
The inability to move around freely was a particular disadvantage, the experts said.
Eric Witte, who worked as an adviser at the ICC and at the Special Court for Sierra Leone, cited the case against Taylor, who is appealing his 50-year jail sentence.
In that case prosecutors retraced the path taken by alleged diamond smugglers as part of their investigation into whether Taylor used proceeds from the illegal sales of "blood diamonds" to finance guerrilla fighters. The experience allowed them to visualize what they were asking witnesses about, Witte said.
"If you know where the river and a bridge is, it can be the reference that allows you to understand the witness's narrative," said Chris Santora, a New York prosecutor who also worked on the team that prosecuted Taylor.
"If you don't know the context you can ask questions that confuse major events, so your witness looks confused even if he wasn't."
Local knowledge helped him to know whether he was being told the truth or not, he added.
"There was this argument the border between Sierra Leone and Liberia was closed, that you couldn't get through because of the heavy forest. But you go there and see it's not a forest, it's a savannah," he said.
This kind of in situ investigation was often not possible in ICC cases because the area was too dangerous or they were not given enough support, the prosecutor's office said.
In the Ngudjolo case, for example, investigators were advised for security reasons not to go to Zumbe, a village that was the subject of witness statements disputed by the defense and rejected by the court, it said.
"All visits by investigators from the prosecutor's office were advised against by all authorities, including the United Nations which was in a position to assist with our movements in Ituri."
The United Nations Department for Safety and Security said it was not aware of any specific advisory to ICC prosecutors in the case.
Judges have also complained of prosecutors failing to check out their witnesses' stories and of using intermediaries who may have had agendas of their own.
In the Ngudjolo trial, witness P-279 testified that he had seen Ngudjolo and his co-accused Germain Katanga enter a school near a military camp.
But when judges visited the site, they found it was impossible to see the school from where the witness had been standing, and criticized the prosecution for not checking this.
"It would have been desirable for the Prosecutor, before the debate about the facts of the matter began, to have been able to visit the places where the accused lived," they wrote in their ruling.
Under cross-examination, P-279's weaknesses as a witness became apparent because of long silences during the testimony, most often "when faced with contradictions he couldn't resolve."
Comparing the ICC to other ad hoc courts from a procedural point of view, legal expert William Schabas said the ICC was more strongly influenced by the French-style inquisitorial legal system versus the English-speaking adversarial systems that guided the Rwanda and Yugoslavia tribunals, although all the courts have been hybrids of the two systems.
As a result ICC judges have limited the practice of "proofing" witnesses - preparing them before they take the witness stand - meaning it was harder to predict how a witness would behave given that months or years might have elapsed between when witnesses were first interviewed and the trial.