Abandoning popularity surveys in ISDS: The value of empirical data
Currently, there is a constant proliferation of directories and rankings within the international legal profession intended to quantify the prestige and competence of arbitration practitioners. Nevertheless, such indicators may be subject to certain biases that could call into question their reliability. At International Arbitration Day at LIDW 2026, which was recently held, Mr. Toby Landau expressed that such directories and rankings tend to reinforce hierarchies based on market prestige as rankings rely heavily on market reputation rather than actual performance. Landau questioned the scientific validity of these systems, as they are often based on opaque methodologies and biases associated with potentially sponsored candidates, prioritising corporate reputation over proven technical effectiveness.
Several external factors can indeed call into question these rankings, ranging from the inherent subjectivity of popularity surveys to the commercial motivations of certain publishing bodies. It is therefore essential to use evaluation methodologies that provide an unquestionable level of technical rigour and empirical objectivity.
In this context, the ranking published a few weeks ago by Investor-State Law Guide (ISLG) stands out due to its completely different methodology: it is based exclusively on technical information obtained from investment arbitration documents available in the public domain, i.e. on the actual documentation and tribunal proceedings. As such, ISLG provides a view free of the biases that often distort information, allowing empirical data and a lawyer’s actual impact on case precedent to take on greater significance.
The ISLG database sets itself apart by providing all public decisions and awards from ICSID, NAFTA and ad hoc tribunals in cases related to investment treaties. This tool represents a comprehensive approach dedicated to research into investment treaty arbitration, and is based on three fundamental pillars: precision, accuracy and comprehensiveness. In contrast to other contemporary platforms, ISLG does not utilize artificial intelligence; awards and decisions are reviewed through multiple layers of scrutiny by human experts, thereby ensuring that methodological rigour underlies every entry in the database.
This methodological approach is particularly relevant when assessing the impact of counsel. As such, ranking among the top ten most frequently cited counsel does not rely on surveys; rather, practitioners are ranked based on the actual frequency of their involvement as counsel in specific investment arbitration cases. Such methodology provides a real-world measure of counsel’s impact and reflects a proven track record in high-profile cases.
Looking at these raw statistical data, what is interesting is how the empirical evidence backs up the technical expertise seen in investor-state arbitration on a daily basis. In fact, this list features lawyers of recognized standing, such as Nigel Blackaby, Paolo di Rosa, Eduardo Silva Romero, Ignacio Torterola and Yas Banifatemi, among others.
Source ISLG: 22 May 2026
All in all, rankings based on verifiable data are particularly valuable in enabling law firms, clients and institutions alike to easily identify the most experienced and influential lawyers in investor-state arbitration. Giving priority to the traceability of procedural actions over popularity scores provides the legal profession with a sound analytical framework that makes it possible to measure legal effectiveness with a higher degree of transparency.
