Navigating investor claims in the wake of US trade actions: Can tariffs constitute investment treaty violations?

Abstract

Tariffs have emerged as the central instrument of President Trump’s “America First Trade Policy” in his second term, justified primarily by asserted emergency and national security concerns and applied across a broad range of imports from states worldwide. Although tariffs are conventionally analysed within international trade law, their scope, design, and administration also raise consequential questions under international investment law, particularly for foreign investors operating in the United States whose rights are protected by International Investment Agreements (IIAs), in the form of Bilateral Investment Treaties (BITs) or Free Trade Agreements (FTAs) with investment chapters. This article examines the circumstances in which affected foreign investors may seek recourse through IIA-based investor–state dispute settlement (ISDS), especially where effective multilateral trade dispute settlement does not furnish a timely or definitive remedy. It situates tariff measures within the architecture of investment protection and argues that, when tariffs are politically motivated, disproportionate, arbitrarily administered, or discriminatorily applied, they may implicate core IIA standards, including national treatment (NT), most-favoured-nation (MFN) treatment, fair and equitable treatment (FET), and protections against expropriation. At the same time, the article assesses the extent to which the United States may seek to preclude responsibility through essential security exceptions, which are a recurring feature of United States IIA practice. Against the backdrop of mounting disruptions across manufacturing, agriculture, and technology, driven by increased operating costs, destabilised supply chains, and diminished competitiveness, the analysis identifies the principal doctrinal pathways and constraints for translating tariff-induced economic injury into viable IIA claims.