Former Sydney tennis coach turned self-styled spiritual healer Serge Benhayon has suffered a spectacular loss in his Supreme Court defamation case against a former client, after a four-person jury found it was true to say he led a "socially harmful cult", "intentionally indecently touched" clients and made "bogus healing claims".

Serge Benhayon, 54, sued acupuncturist and former client Esther Rockett for defamation over a series of blog posts and tweets starting in November 2014, which he says portrayed him as "dishonest", a "charlatan who makes fraudulent medical claims", and the leader of a "socially harmful cult".

Serge Benhayon, centre, outside the Supreme Court during his defamation case against Esther Rockett. Credit:AAP

Mr Benhayon, a former bankrupt who operates the lucrative business Universal Medicine from his home near Lismore in the NSW Northern Rivers region, described himself in court as a "teacher" and "practitioner" whose healing techniques included "esoteric breast massage", which is taught by him but performed exclusively by women.

During his stint in the witness box, Mr Benhayon also said he "had an understanding" that in one of his many past lives he was Leonardo da Vinci.