Between 1993 and 1998, Mr. Abi-Antoun was a Judicial Aider and a Head-Clerk of the Instant Court of Beirut, and was assigned twice as a Notary Public in Beirut.
Between 1994 and 1998, he was delegated by the Ministry of Justice to the "Arab Center for Juridical and Judicial Research" for the "Arab Countries' League" under the auspices of the "Council of the Arab Ministers of Justice".
In May 2008, he was assigned by the "National Center for State Courts (NCSC) as the "Court Administration Consultant" for "Lebanon Judicial Strengthening Project", a project developed and managed by and for the "United States Agency for International Development" (USAID).
Besides his Legal diverse engagements, Mr. Abi-Antoun is a Board member of an American-Lebanese Pharmaceutical/ Bio-Chemical Joint-Venture based in Nashville - Tennessee, and Dbayeh - Lebanon; and was, for five consecutive years, a board member of an international IOT leading company based in Los Angeles - California, USA.
For more than thirty years, he participated, with leading roles, in more than 15 charitable and Societal Organizations, such as the Lebanese Red Cross, UNICEF, Terre des Hommes, UNIPADH, and ANU-LIBAN, amongst others.