He served as a professor of law at several Lebanese Universities. Professor Harb was the legal counselor of several Lebanese Ministers (1982-1990). Professor Harb has more than 40 years of experience in the areas of reform and development of the justice sector in the MENA Region. He served as a Senior Rule of Law advisor with several international and Regional Institutions mainly the World Bank (1995-1998), UNDP-POGAR (2000-2010), ESCWA, EU, etc. Most recently, as Senior Rule of Law Expert, he participated in the preparation of the Iraqi National Strategic Plan for the Rule of Law (UNDP-Iraq 2012-2014); Provided Technical Support to Strengthen the Role of Inspectors Generals (IGs) within their Ministries in Iraq (UNDP-Iraq 2014).