Archbishop Mgr Joseph Mercieca was born in Victoria on November 11, 1928. He was educated at the Gozo seminary and continued his studies at the Gregorian and Lateran universities in Rome.

He was ordained priest on March 8, 1952. Between 1959 and 1969, Pope Paul VI appointed him judge of the Roman Rota. This is an ordinary court of appeal for cases referred to the Holy See. It is best known for its competence and decisions in cases involving the validity of marriages.

He was also adviser of the Congregation for the Sacraments and the Congregation for the Doctrine of the Faith.

On July 27, 1974, he was appointed Auxiliary Bishop to the late Archbishop Mgr Michael Gonzi. Two months later, on September 29, he was consecrated Bishop in a ceremony at St John's Co-Cathedral led by Mgr Gonzi.

On December 12, 1976, Mgr Mercieca was installed as Archbishop of Malta following Mgr Gonzi's retirement after 36 years of service.

On June 11, 1991, Mgr Mercieca was nominated member of the Supreme Tribunal of the Apostolic Signature, whose main tasks are to resolve questions dealing with juridical procedure and to supervise the observance of laws and rights at the highest level. It decides the jurisdictional competence of lower courts and has jurisdiction in cases involving personnel and decisions of the Rota. It is the supreme court of the state of Vatican City.