Delivering its first sentence, the International Criminal Court jailed Congolese warlord Thomas Lubanga Dyilo for 14 years on Tuesday for recruiting child soldiers.
The Hague-based court was set up a decade ago to punish and discourage the world's worst crimes through a new system of international justice, but its critics say it has moved too slowly and failed to put its most important suspects on trial.
Lubanga was found guilty in March of abducting boys and girls under the age of 15 and forcing them to fight in a war in the east of Democratic Republic of Congo in 2002 and 2003.
At least 60,000 people are thought to have been killed in that chapter of a wider Congolese war.
"The trial and sentence handed down today sends a strong message to those who recruit and use children during times of war," said Anneke van Woudenberg of Human Rights Watch.
But taking into account the six years Lubanga spent in detention during the trial, Lubanga's sentence has only eight years to run. He could get parole earlier.
Critics of the International Criminal Court questioned how big an achievement it could claim from sentencing Lubanga.
"If you'd said at the beginning, this court would finish one trial in 10 years, and that would be for a secondary offence like using child soldiers, people would have said they won't waste their money on it," said William Schabas, a law professor at Middlesex University.
Some Congolese were also disappointed in Lubanga's sentence, which compares to the 50 years handed down in May by another court in The Hague to former Liberian president Charles Taylor for war crimes in Sierra Leone.
"We had hoped he would stay in prison for life in order to ease the minds of the victims," said Emmanuel Folo, a human rights lawyer in Ituri.
Presiding judge Adrian Fulford criticised the ICC's founding prosecutor, Luis Moreno-Ocampo, for his conduct of Lubanga's case. Moreno-Ocampo, who recently completed his term, did not respond to a request for comment.
Lubanga's sentence was shortened because of his good behaviour in the face of the prosecutor's failure to disclose some evidence and giving misleading statements to the media, Fulford said.
Dressed in a grey suit, blue shirt and tie, Lubanga's initial wariness gave way to growing confidence as Fulford criticised Moreno-Ocampo.
Lubanga's Union of Congolese Patriots fought against militias from the Lendu ethnic group, including the Congolese Popular Army and the Patriotic Resistance Force in the Ituri region.
The conflict was part of a wider war in Congo in which several million people are thought to have died.
Fighting continues in eastern Congo.
"Local populations, including children, continue to be exposed to the dramatic consequences of war at the hands of armed groups," the prosecutor's office said in a statement.
It said it hoped to bring new charges of murder, sexual slavery and pillaging against Bosco Ntaganda, another militia leader and erstwhile ally of Lubanga.
Some of Moreno-Ocampo's detractors said he had focused too strongly on bringing prosecutions mainly against Africans.
But both Moreno-Ocampo and his successor Fatou Bensouda, who is from the West African country of Gambia, have said that is because the worst atrocities were committed there.
Supporters of the court say its focus on Africa has made up for the shortcomings of local justice systems.
Suspects before the court include Laurent Gbagbo, the former president of Ivory Coast, who is in The Hague awaiting confirmation of charges of crimes against humanity in his country. But others remain at large.
Those include President Omar Hassan al-Bashir of Sudan, indicted by the court in 2009 and accused of war crimes in Darfur.
Then there is Ugandan warlord Joseph Kony, the subject of a worldwide internet campaign last year, who is accused of enslavement and using child soldiers.
The International Criminal Court's record compares to more than 60 people convicted by the International Criminal Tribunal for the Former Yugoslavia since it was set up in 1993.
"The ICC must ensure it learns the lessons of the first 10 years and challenge those who argue international justice is too costly and lengthy," British Foreign Minister William Hague said on Monday.
But even if US opposition to the court under President George W. Bush has given way to tacit support under Barack Obama, it is still constrained by its political environment.
It is unable to prosecute alleged atrocities in Syria, for example, because Syria never signed the Rome Statute establishing the court.
The ICC could still bring prosecutions if it had a referral from the United Nations Security Council - but that has so far been vetoed by Russia.