The apprehension of former Bosnian Serb leader Radovan Karadzic opens the door not only to bringing an important accused war criminal to justice but also to a brighter future for Serbia.

Radovan Karadzic has been a thoroughly bad actor since the beginning of the troubles in Bosnia-Herzegovina in 1992. He was a psychiatrist by training -- in principle a healer of troubled minds -- but in practice he acted as the leader of an ethnically based group of secessionists who killed and terrorized thousands of people of the other faiths and ethnicities of his tormented country.

Mr. Karadzic's Serbian Orthodox separatist regime presided over many of the atrocities that plagued the former Yugoslavia in the 1990s. These included the shelling of the Bosnia-Herzegovinian capital, Sarajevo, a former host of the Winter Olympics, and the brutal massacre of an estimated 8,300 Muslim men and boys in Srebrenica, a town that has come to have as much significance as Guernica in Spain and the Nazi concentration camps for the tragedy that occurred there.

Serbia's willingness to protect Mr. Karadzic and his Bosnian Serb military counterpart, Gen. Ratko Mladic, from being brought before an international tribunal has -- from the Dayton Accords, which in 1995 brought the war to an end in Bosnia-Herzegovina, until Monday, when the Serbian government announced his capture -- constrained the European Union in moving forward Serbia's aspirations to join. It is generally accepted that EU membership will be the key to political modernization and economic development in Serbia, a nation of 10 million that now lags behind most of the rest of Europe in both those fields.

Serbia's election in February of a president, Boris Tadic, who is considered to be pro-Western and who strongly favors Serbia's moving forward on EU membership, democratization and economic modernization, opened the door to handing over Mr. Karadzic. For the Tadic government to kick him off the sled was no mean feat in Serbian political terms. The Serbians and some Bosnia-Herzogovinians have known where Mr. Karadzic was for years, but chose to protect him, based on what was perceived as his contribution to the Serbian nation during the bitter years after the breakup of Yugoslavia.

Mr. Karadzic will now presumably go before the International Criminal Tribunal for the Former Yugoslavia in The Hague for trial, as did former Yugoslav President Slobodan Milosevic. Milosevic died before his four-year-long trial was completed. There might be some hope that the trial of Mr. Karadzic will proceed more efficiently.

The other next step is that the Serbians should hand over Mr. Mladic, easily as evil as Mr. Karadzic, whose location they also no doubt know. His protectors are his former military colleagues, which will provide a test for Mr. Tadic's civilian government.