In 1998 Rapoport was appointed as a member of the Chief Rabbi's Cabinet and Advisor to the Chief Rabbi, Jonathan Sacks, on matters of Jewish Medical Ethics and served in this position until the retirement of Rabbi Sacks in 2013. In this capacity, he served as the Chief Rabbi's spokesperson to the media and as an intermediary between himself and the British medical establishment and several other prominent organisations. During this period Rapoport gave a regular lecture to the United Synagogue Rabbinate at the London School of Jewish Studies.