Judge Riachi is vice-president of the tribunal. His career has been principally in the Lebanese justice system. Judge Riachi began his career as counsel in 1971. From 1976 to 1981 he served as counselor at the Service des législations et des consultations in the Ministry of Justice. For nearly 11 years after that he was president of the Commerce Tribunal in Beirut. He served as attorney general in the Financial Public Prosecutor's Office (1992-1993).
From 1993 to 1995, Judge Riachi presided over the Court of Appeal of Mount Lebanon. He also served as president of the Disciplinary Council for Judges and was a member of the Lebanese Supreme Council of the Judiciary until December 2008. Judge Riachi was elected ad litem judge at the International Criminal Tribunal for the former Yugoslavia in 2000. Until his appointment to the tribunal Judge Riachi served as president of the Criminal Chamber in the Lebanese Court of Cassation and was a member of the Court of Justice.
In addition to his judicial appointments, Judge Riachi has been a law professor lecturing on criminal procedure at the faculty of law at Saint Joseph University of Beirut, the faculty of law at the Université du Saint Esprit de Kaslik and at the Institut d'études judiciaires of Beirut. In March 2009, he was elected vice-president of the Special Tribunal for Lebanon.