Voices in law and climate: Diane Harris on career, climate contracts and green infrastructure

An interview with Diane Harris, Partner at MDY Legal.

Diane Harris is an established legal professional with two decades of expertise across both the private and public sectors. Her law firm specialises in providing legal advice on the structuring, establishment, public procurement, as well as the governance and financing of social and economic development initiatives. She sat down with Regina Villaruel, our Head of Finance and Capital Markets, to share insights into her career journey, the intersection of law and climate, and how best to integrate climate-conscious practices into infrastructure projects.

Regina Villaruel: Can you tell us about your current role and focus area?

Diane Harris: I’m a partner at a law firm that primarily works in the international development sector. Our clients are typically organisations funded by government aid departments, such as the UK Foreign, Commonwealth & Development Office, and European and international equivalents. Our main focus is impact—poverty reduction, economic growth, green and responsible business, and climate change, all with a strong focus on gender equality, diversity, and inclusion, and safeguarding. Most of our clients operate in the infrastructure or financing sectors.

That sounds interesting. How did you get into that?

From the outset, I knew I wanted to use the law as a tool for protecting human rights, which led me to study Law and German at university.

After graduating, I worked at a medical charity for five years. At that time, if you wanted to do the Legal Practice Course (LPC), you had to complete it within a few years of finishing university. So, I studied part-time while working. Once I completed the LPC, I knew I didn’t want to work for a big city firm and that I wanted to work somewhere focused on social impact.

I initially considered human rights law but realised that it required background training in criminal law, which wasn’t for me. Instead, I looked for something aligned with my human rights principles, and I came across my current firm in a Law Society advert. I interviewed, got the position, and have been there ever since.

Over the years, I worked closely with the Private Infrastructure Development Group (PIDG), an impact investor, which we helped set up in 2001 on behalf of the UK and European governments. That experience completely shaped my legal career, and now I’m back at my firm full-time, helping companies operate sustainably and responsibly, using the lessons learnt from PIDG.

Were there any mentors who influenced your career?

Absolutely. My fellow partners at MDY Legal played a significant role in shaping the type of lawyer I am. The directors at PIDG were also inspiring – they balanced a strong commitment to responsible business with savvy business acumen.

Another mentor was (and still is) an American woman who left Wall Street in the 90s to pursue a career with social impact. She recognised gender and workplace inequalities and always went out of her way to support others, particularly women. She showed me that you can be a successful businessperson while staying true to ethical principles.

It was clear to me that similar principles could be applied to climate-conscious contracting, which led to the development of climate clauses like Callum and Theo’s Clause with the Chancery Lane Project.

What are some of the main challenges and opportunities in getting organisations to adopt greener infrastructure practices?

The biggest perceived challenge is cost. Many companies assume that adopting low-carbon practices will be more expensive. This is where financial institutions can play a crucial role – by encouraging or requiring sustainable practices rather than just using financial leverage as a stick.

There’s also a knowledge gap. Some organisations don’t fully consider the economic opportunities of decarbonising and the material risks of not. Businesses worldwide are already facing the effects of climate change, whether through flooding, supply chain disruptions, or lost workdays – and it is not going away.

A lack of a joined-up policy is another issue. Too often, there are inconsistencies in government regulations across sectors and regions. Without a clear, unified approach, it’s difficult for businesses to implement meaningful change.

Has awareness improved over the years?

There’s definitely a divide. Action is often focused on mitigation rather than adaptation. Mitigation – decarbonisation – is crucial, but it’s a preventative measure designed to meet the Paris Agreement. Many companies see climate as a long-term challenge, which can delay action. Meanwhile, climate change is already here. Extreme weather events and other impacts are happening now, and the world will continue to change regardless of whether we limit warming to 1.5°C. That’s why adaptation is just as crucial. 

Climate-related extreme weather events are happening everywhere, yet there are still many who don’t see the urgency.

Let’s take Bangladesh as an example. As one of the most climate-vulnerable countries, it is already experiencing severe impacts, making the risks (and the urgency of adaptation) impossible to ignore. While mitigation is essential for long-term resilience, businesses are facing climate-related disruptions now, making adaptation a pressing priority. One colleague working in Bangladesh has shifted her approach when engaging with businesses, moving away from abstract climate discussions and instead asking if they have experienced flooding. When they recognise the financial and operational losses firsthand, it helps them connect the dots. This kind of real-world framing is crucial in demonstrating why both mitigation and adaptation must be embedded into business strategies today.

What should organisations consider when incorporating green practices?

A holistic approach is crucial. Sustainability should be embedded at every level, starting with company constitutions and governance structures. Boards need the right expertise and resources to implement green strategies effectively.

From there, sustainability should be reflected in procurement, investment policies, HR, and even banking decisions. Contracts should be aligned with environmental commitments, and companies should provide technical assistance to smaller suppliers who may need support in meeting sustainability requirements. It has to be a standard, ingrained part of business operations rather than an afterthought or silo activity.

What are the barriers to integrating climate clauses into contracts?

The main barrier is the legal sector’s reliance on precedent. There’s a strong preference for “market standard” contracts, and anything that deviates from that is often met with resistance. Clients may want to do the right thing, but hesitate if a clause isn’t widely used.

That’s why “winning hearts and minds” is so important. Businesses may be committed to sustainability in principle but unsure about the practical implications. Breaking it down for them and showing that change happens incrementally can help shift perspectives.

Finally, what advice would you give someone looking to drive climate action within the legal sector?

Don’t give up. There will be easy wins, but also challenges. Change in the legal sector happens gradually, and you might not always get everything you want straight away. But keep pushing, keep educating, and keep making the case for responsible business practices. Over time, the small shifts add up, and that’s how real progress is made.