Investor-State Disputes in the UK: 2025 in Review

2025 was a watershed year for investor-state disputes in the United Kingdom. We take a closer look at some of the year’s defining moments, including the first ICSID claim brought against the UK and pivotal judgments handed down by the English courts.

The UK’s first ICSID claim

On 8 August 2025, the first ICSID claim with the UK as respondent state was registered (ICSID Case No. ARB/25/37). The claimants, Woodhouse Investment Pte Ltd and its Singaporean parent company, West Cumbria Mining (Holdings) Ltd (“Woodhouse”), are investors in the West Cumbria Mining project. Woodhouse initiated ICSID proceedings under the 1975 UK-Singapore Bilateral Investment Treaty following the High Court’s decision in September 2024 to quash the planning permission previously granted for the project, after two environmental conservation organisations successfully challenged the decision.

This case illustrates the continuing tension between climate policy and ISDS mechanisms. Commentary following its announcement echoes the broader debate surrounding the Energy Charter Treaty (“ECT”) withdrawal, with some calling for governments to withdraw from treaties and agreements containing ISDS provisions to protect climate action from investor claims.

Key Judgments of the English courts

2025 also saw significant English court judgments which clarified the application of state immunity, issue estoppel, and award assignability to investor-state disputes. These judgments present both opportunities and obstacles for award creditors seeking to enforce arbitral awards against sovereign states in the UK.