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Hannah Ambrose is a partner in our global arbitration and public international law teams, based in London. She has experience in both commercial and investment treaty arbitration in a number of sectors and advises on a range of public international law matters including state immunity and immunity of international organisations. She was promoted to the partnership on 1 May 2023.

What has your path to partnership looked like? 

I qualified into the international arbitration group in London at another firm. I was intent on being a disputes lawyer – I couldn't see myself doing anything else. I was particularly drawn to the international aspects of arbitration and the opportunity to do the advocacy. And I can't say that I was sad that the White Book would not be a regular feature of my practice! I was also attracted to the idea of working on commercial disputes; but I was really interested in the public international law work too, in particular the confluence of law, policy and public interest often found at the heart of investment treaty arbitration. I have deliberately kept a mixed commercial/international law practice throughout my career. 

I worked in a busy arbitration practice for a number of years before I had my first daughter. I had a bit of a non-traditional route from there, job-sharing as a senior associate with Vanessa Naish. Although it was a pretty novel arrangement at the time, we had the support of colleagues and clients and continued to enjoy a mixture of interesting commercial and investor-state work. 

Then, after daughter number two, looking for a new opportunity but wanting to keep hold of a solid and productive working relationship, Vanessa and I joined Herbert Smith Freehills together as professional support lawyers and practice managers for the global arbitration practice, still job-sharing. We didn't know whether we could move firms together but we thought, if you don't ask, then you don't get! It was very forward-thinking of Herbert Smith – as it then was – to take on the pair of us, and still we have not come across any other lateral hire of a job-share. 

It was the perfect role to build my internal network, as well as to focus on the financial management, people management and business development side of a successful practice, while keeping my technical knowledge sharp. All of these aspects of the role have served me in really good stead as my career has developed. Although it was an enjoyable and challenging period, I missed focusing on client work and building client relationships, so I moved back to fee-earning in late 2018. I immediately got stuck into some very interesting cases and have really enjoyed moving back to managing matters and delivering strategic advice. Since I returned to fee earning, I have done a lot of oil and gas-related work, but also focused on pharma and life sciences and banks and financial institutions. 

You have a broad practice, with a particular focus on public international law. What attracted you to public international law and what are the current trends you are seeing? 

I would love to say that my interest started back in university but in reality I missed that opportunity completely and gravitated towards public international law work once I had qualified. It is a really intellectually interesting area of practice with real-world consequences for both commercial and state clients. Investment arbitration is a significant limb of our work and that is where my interest in international law grew from. 

In terms of trends, the international law and soft law commitments towards addressing climate change and the pursuit of net zero demand a shift in domestic energy policy for many countries, and the consequent legal changes are likely to continue to lead to investor-state disputes as well as climate-change related human rights-based litigation. This impacts both our commercial and state clients. Of course, international law is fundamental to address significant geopolitical events such as Russia's invasion of Ukraine and many commercial clients are looking to international law protections, under investment treaties and other international law instruments, to address the impact on their businesses. International law commitments continue to be relevant beyond the energy sector – resource nationalism affects our mining clients in particular, but a broad range of state action may give rise to an investment treaty claim. We are seeing, for example, increased state control of data flows; sector-based antitrust legislation; opportunistic demands for capital gains tax on high-profile transactions; imposition of windfall taxes, reassessment of taxation models (eg, for gig economy), refusal to handover VAT rebates, and/or withdrawal of exemptions.

Clients across all sectors are vulnerable to significant, or even existential, impacts of state actions which is where investment treaties come in. 

You also work with many financial institutions, who historically referred their disputes to court rather than to arbitration. Why has this started to change? 

I don’t think financial institutions are turning away from the courts, particularly the English courts, which are often the preferred forum for efficient and cost-effective resolution of many of their disputes. But most of our clients in this sector have always operated nuanced dispute resolution policies which point to international arbitration in particular when there is no clear path to enforcement of an English court judgment against the counterparty. Given there is no international treaty for reciprocal enforcement of judgments to rival the New York Convention 1958, arbitration has its place in many different types of transaction, particularly in the loan and derivatives markets.

While favouring court litigation, clients in the sector tend to include more arbitration clauses than they expect and are increasingly curious as to how they can turn the procedural flexibility and party autonomy inherent in the arbitral process to their advantage. The ability to choose an arbitrator with practical sector experience, and more limited production of documents can also be valuable in the right circumstances. The moves among the institutions to make their rules more sector-friendly have helped, such as empowering the tribunal to dismiss unmeritorious claims and defences on a summary basis. The fear factor has certainly been reduced. 

You have done a lot of pro bono work in your practice, including for the Government of Sierra Leone. What is the impact of this work and what do you see as the professional benefits? 

I have been really proud to be involved with Fair Deal Sierra Leone. The broad aim is to help to build capacity and to support development outcomes, in circumstances where Sierra Leone does not have sufficient financial, legal and/or human resources. Our work since 2010 has been varied and has included supporting deal negotiation with international investors, building capacity to redress the balance when negotiating with large well advised international investors, training and provision of other resources in support of capacity building, in London as well as Freetown, and work on the development of new legislation and promotion of the rule of law. I have been lucky to work on both the accession to the New York Convention and the development of new arbitration legislation, among other things. 

There are many professional benefits: interesting work which contributes to an international development agenda and sustainable change, the opportunity to build long lasting client relationships and friendships, personal development outside my usual working environment, and exposure to Ministers, civil servants, governmental advisors, and the diplomatic and international development communities. It really is a unique experience and one I can highly recommend. 

Independently of the Fair Deal work, I was also fortunate enough to be part of the team supporting Bridges Outcomes Limited on their participation in the Sierra Leone Education Innovation Challenge – a pay-by-results contract where the upfront investor is repaid based on the educational outcomes achieved. This is just the tip of the iceberg in terms of the pro bono opportunities available at the firm. 

What is your career highlight so far? 

There have been so many! If I'm going to pick then perhaps my first hearing in the Peace Palace in the Hague and being on the right side of a Court of Appeal judgment upholding an anti-suit injunction to prevent threatened proceedings challenging an arbitral award in our client's favour. It was a very hard-fought arbitration for one of the loveliest clients. 

What do you like to do to relax? 

Running, eating, and shopping – online or in person. At least half of it goes back, honest!


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Hannah Ambrose

Partner, London

Hannah Ambrose

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