John practises widely in all aspects of complex commercial disputes - trials, appeals, representative proceedings, regulatory matters, public law issues, commissions of inquiry and domestic and international commercial arbitrations. He has advised and acted for prominent Australian and foreign corporations, and for regulators. Banking and finance and corporate law have been a particular focus of his work.
Apart from his advice and appearance work, John also acts as mediator and arbitrator. He was a member of the Australian Takeovers Panel from 2014 - 2020.
John is a Fellow of the Australian Academy of Law, a founding member of Maxwell 42 Chambers in Singapore and an associate member of South Square Chambers, Grays Inn, London.
Chambers & Partners Asia Pacific Guide – Star Individual for Dispute Resolution - is identified by several sources as one of the few barristers who can truly be said to "sit at the top of the Bar." He is characterised by one interviewee as an "outstanding advocate," distinguished not only for his "mastery of the courtroom," but also for his "easy rapport with the Bench and for working well with everybody on the team, winning by being engaging, not aggressive." Other sources speak of his ability to "communicate with boardrooms in a way that resonates with them" and of the "stellar job" he does of handling "absolute bet-the-farm cases."
Chambers & Partners Asia Pacific Guide – Band 1 Restructuring/Insolvency Senior Counsel - “a very eminent practitioner and is very good in the insolvency space," and "John Sheahan is always our go-to senior counsel."
Doyles Guide - Leading Dispute Resolution and Commercial Litigation Senior Counsel
Doyles Guide – Preeminent Insolvency & Restructuring Senior Counsel
Best Lawyers – Banking and Finance Lawyer of the Year (2019) and ranked for for bet-the-company litigation