Mr. Charles Taylor, former president of Liberia, has been convicted of aiding and abetting war crimes and crimes against humanity. The judgment on April 26 by the U.N.-backed Special Court for Sierra Leone on the premise of the International Criminal Court in The Hague is the first against a former head of state by an international court since the Nuremburg trials that followed World War II. It is a long overdue reminder that no one is immune from justice.

Mr. Taylor was charged with arming rebel groups in the neighboring country of Sierra Leone in exchange for "blood diamonds,"—diamonds mined from war-torn regions. The indictment alleged that those rebels engaged in a sustained campaign of terror during a civil war that included rape, murder, sexual slavery and the enlistment of child soldiers. It is estimated that some 50,000 people died during the conflict. The rebels Mr. Taylor financed were known for especially gruesome acts of violence, such as hacking off the limbs of enemies with machetes.

Mr. Taylor was indicted in 2003, arrested in 2006, and eventually extradited from Nigeria where he had taken up residence to The Hague to stand trial. The five-year trial included 94 witnesses for the prosecution and 21 for the defense. The judges deliberated for a year before returning a verdict of guilty on charges that he provided "sustained and significant" support for the rebels. He was found not guilty of ordering the abuses or controlling the soldiers. The reading of the judgment, which included details of the crimes, lasted two hours. Mr. Taylor will be sentenced on May 30.