This special issue of Investment Treaty News examines the changing landscape of international investment agreements (IIAs) and the growing role of treaty data in informing evidence-based policy choices. The issue is co-edited with Dafina Atanasova and informed by two major UN Trade and Development (UNCTAD) data releases in 2025: the new UNCTAD IIA Facilitation Mapping database, which maps facilitation-related content across more than 400 investment treaties concluded since 2010; and the largest update of the UNCTAD IIA Content Mapping database since 2017, covering over 200 additional IIAs, including all broad economic agreements with substantive protection content, and bringing the dataset up to date for the period 2017–2024. Both dataset updates are analyzed in a recent UNCTAD report on the state of play of IIA reform. Together, these resources offer a useful, granular view of how IIAs have evolved in recent years. Complemented by the UNCTAD Investment Dispute Settlement Navigator, they also provide a foundation for the kind of empirical analysis that has long been called for in a field where treaty-making often outpaces systematic evidence on what works. The contributions in this issue approach the relationship between treaty data, treaty design, and practice from complementary angles.

Joshua Paine’s contribution examines the growing trend of including joint committees in IIAs—institutional bodies tasked with facilitating ongoing cooperation between treaty parties. Drawing on UNCTAD’s mapping data, Paine observes that 60% of IIAs concluded between 2020 and 2024 include a committee, a marked increase from earlier periods. His piece sketches a research agenda around the diverse functions conferred on these committees and highlights a key challenge: we still know remarkably little about whether and how these bodies operate in practice and whether they support meaningful, lasting cooperation. As Paine argues, closing this knowledge gap is essential for evidence-based policy-making on institutional design for IIAs.

Writing in her personal capacity, Mariana Pinto Schmidt offers a negotiator’s perspective drawing on her experience in Chile, a country that has actively engaged with the evolving investment treaty landscape. Her piece illustrates how a state can pursue coherent treaty design—clarifying protection standards, managing overlapping treaty networks, and incorporating facilitation and sustainable development commitments—while working within constitutional and regulatory constraints. Pinto Schmidt’s contribution also highlights the practical relevance of comparative data and UNCTAD’s mapping tools for informing negotiation strategy and maintaining consistency across a treaty network. She stresses that treaty data are key tools to support and inform governmental policy, rather than to drive it.

Lise Johnson’s contribution examines the importance of public access to information on treaties and ISDS for diagnosing systemic problems and informing reform. Drawing on concrete examples—from the use in negotiations to the costs of defending ISDS claims, from the practice of double-hatting to the debates on third-party funding disclosure at UNCITRAL—Johnson shows how publicly available data have been indispensable to identifying concerns and evaluating proposed solutions in treaty-making as well as ISDS reform. Her piece also considers the limits of current transparency, noting that partial access can itself distort reform debates, particularly when the evidence needed to justify regulation cannot be gathered without first mandating disclosure. Johnson argues that as the volume of treaties and awards continues to grow, transparency and accessibility—through searchable, freely available databases—must grow commensurately.

A common thread across the contributions is the recognition that the international investment regime is in a period of significant, if uneven, transformation. Investment treaties are no longer viewed primarily through the lens of investor protection and dispute settlement; institutional cooperation, regulatory coherence, and new approaches to facilitation are increasingly shaping treaty design. Yet, as these contributions make clear, meaningful reform depends on the availability and use of reliable data—on treaty content, on institutional practice, and on the real-world operation of commitments that states have undertaken.

We hope this issue contributes to that effort and invites further engagement from researchers, practitioners, and policy-makers alike.

The authors’ opinions and views expressed in this article are expressed in their personal capacity.