The Bosnian Serb leader Radovan Karadzic has been sentenced to 40 years in prison for atrocities committed in the Bosnian war of 1992 to 1995.
The conflict was an appalling episode in modern European history.
It was a complex ethnic feud that some outside observers tried to understand in a black and white way, and often in a way that demonised the Serbs, without any understanding of the overall context.
Terrible crimes were carried out by all sides.
However, Bosnian Serb militias were indeed responsible for the most unforgivable and evil single atrocity of the entire Balkan wars, the Srebrenica massacre of 1995.
The calculated slaughter of 8,000 Muslim men and boys was a horror without parallel on the continent since the Second World War. As the UN court heard yesterday, it was not a random or spontaneous act, but rather a planned operation.
For the wellbeing of humanity, therefore, it is important that people have been brought to justice.
Mr Karadzic will now pay for his culpability, and as a man aged 70 is likely to die in confinement.
It would not have been unjust if he had suffered a much greater penalty. The Conservative MP Bob Stewart, who as Colonel Bob was a UN military peacekeeper, thinks that Mr Karadzic should have been sentenced to death.
International law is a fragile concept. It is hard to envisage military leaders of major powers, now including countries such as China, ever being put in the dock.
But for all the unevenness of the system, there is a growing likelihood that commanders who are responsible for crimes against humanity will face some international justice. This is a potential deterrent in a world which is still so perilous.
In some respects, as the rise of Isis illustrates, the planet is more dangerous than it has ever been. Anything that might make brutal men pause before perpetrating wicked crimes against civilians is to be welcomed.