On April 5, 2019, Daniel Behn posted at the blog of the European Journal of International Law an extensive article named “Investment Arbitration and its discontents: An Empirical Assessment”, which is authored by Malcolm Langford, Daniel Behn and Laura Letourneau-Tremblay. According to the authors, the legitimacy crisis in international investment arbitration continues to generate attempts at systemic reform. The latest act is playing out in the theatre of UNCITRAL, which is wrestling with issues such as excessive costs, outcome bias, and lack of arbitral independence. Yet, not everyone is certain that there is a problem and some participating states have queried the critiques and their empirical basis. So, what is the state of the evidence? Which critiques deserve serious consideration? These and more questions are being entertained by the authors in this article, which can be viewed from the website of the European Journal of International Law, www.ejiltalk.org.