Decisions of international courts and arbitrators, as well as judgments of national courts, are fundamental elements of modern public international law. The International Law Reports is the only publication in the world wholly devoted to the regular and systematic reporting in English of such decisions. It is therefore an absolutely essential work of reference. Volume 171 is devoted to the United Kingdom Supreme Court judgment of 24 January 2017 in R (Miller) v. Secretary of State for Exiting the European Union (together with judgment of the High Court), The Arctic Sunrise Arbitration (2014 award on jurisdiction and 2015 award on the merits) and the WTO Peru-Additional Duty on Imports of Certain Agricultural Products (Complainant: Guatemala).