Profile
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Position
Jonathan practises across all Chambers’ areas of expertise, including international arbitration, public and private international law, shipping, banking, and commercial law generally. He has acted for states and investors in investment treaty arbitrations, under both the ICSID Convention and the UNCITRAL rules. Jonathan has also acted for companies in international commercial arbitrations under the ICC, LCIA and LMAA rules. He is also appointed to the Attorney General’s Public International Law C Panel of Counsel.
He initially qualified as a solicitor in Australia, practising in commercial litigation, before working as an associate to Justice Crennan of the High Court of Australia. Jonathan was also a senior associate at Hogan Lovells in London, specialising in investment treaty arbitration, public international law and international arbitration.
Prior to joining the bar, Jonathan was a research assistant to Professor James Crawford (now Judge Crawford of the International Court of Justice) and completed a doctorate on international dispute settlement at the University of Cambridge under Professor Crawford’s supervision. Jonathan was also an assistant to the Bahrain Independent Commission of Inquiry.
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Testimonials
Collated independently by Legal 500 research team.
- 'Arron Zitver is responsive and approachable.'
- 'Jack Leppington has been very helpful, always responsive and on top of the issues we raise with him. Pleasant to deal with.'
- 'Good clerking across the clerks room, led by the excellent Chris Theobald.'
- 'The clerks at Twenty Essex have been a pleasure to deal with over the years. They’re straightforward, reliable, and always quick to respond—no fuss, just very capable. They understand how to make things work, especially when timelines are tight or arrangements are complex. That kind of support behind the scenes really matters, and they get it right.'
- 'The service from the clerks’ room has been exemplary. The clerks are highly professional and possess an in-depth understanding of the barristers’ capabilities. They always anticipate our needs, ensuring that all administrative aspects of our instructions are handled efficiently, from scheduling conferences to coordinating document exchanges.'
- 'Twenty Essex has broadened out its offering and is now a top player across commercial arbitration and commercial Chancery work.'
- 'They have one of the strongest sets for international arbitration, with very capable barristers at all levels.'
- 'There’s a real depth of talent across the chambers, but what stands out is how practical and grounded their advice is. They’re not just technically strong—they bring a strategic mindset and are clearly used to handling complex, high-stakes matters. Working with them feels like a genuine partnership, and their barristers are responsive, thoughtful, and always well-prepared.'