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Former Bosnian Serb leader Radovan Karadzic took the stand at his war crimes trial in The Hague this week to defend his dream of an independent Bosnian Serb state, calling his cause during the 1990s Bosnian war "just and holy." The war has been over now for 14 years, but in Bosnia, many fear the question of independence for the country's Serbs could be reopened, this time not with guns and bombs but with a referendum.

One of the provisions of the U.S.-brokered Dayton Agreement that ended the war in 1995 was that Bosnia would be split into two largely self-governing regions — the Federation of Bosnia and Herzegovina, made up mostly of Bosnian Muslims and Croats, and the Republika Srpska, made up mostly of Serbs. For years, the current leader of Bosnia's Serbs, Milorad...