By Elizabeth Blunt BBC Africa analyst

Child soldiers have been used in conflicts across West Africa

This opens the way for what will be the first ever prosecution for child recruitment at an international war crimes tribunal.

The picture of a child soldier, clutching a gun almost as big as himself, has become the enduring image of West Africa's civil conflicts.

Both sides in Sierra Leone used very young fighters, in defiance of international conventions on the rights of the child, and leaders from both sides now face prosecution.

But former deputy Defence Minister Hinga Norman, who recruited and armed pro-government militias, argued that despite these international conventions, and despite general disapproval of under-age recruitment, it actually was not a war crime under international law at the time the acts were committed.

Individual responsibilities

One of the appeal judges agreed with him.

But in the end the panel ruled, by a majority of 3-1, that it was indeed internationally recognised as a war crime in 1996, and the prosecution can go ahead.

The decision turned on the exact point at which something accepted as being against an international convention crystallises into a crime for which an individual can be prosecuted.

By the time the statute of the International Criminal Court was drawn up in 1998, child recruitment was there in black and white as a serious violation of the laws and customs applicable in international armed conflict.