25 years after Srebrenica massacre, int'l crimes are still difficult to prosecute

In 1990, Bosnian Serb forces killed about 8,000 Muslim men and boys during the Balkan conflict in what's now known as the Srebrenica massacre. It was the worst atrocity on European soil since World War II. But 25 years on, war crimes and crimes against humanity are rarely prosecuted. David Scheffer, who was the US ambassador-at-large for war crimes issues from 1997 to 2001, explains why.