Yves here. This post usefully addresses whether the cudgel Trump has used with such glee and abandon, that of threatening to impose big tariffs on countries from whom he wants to extract concessions, is legit. Admittedly even before getting to the question of legality, there is a “possession is nine-tenths of the law” aspect, that even if the tariffs were illegal, getting that into and reversed by a forum with jurisdiction would take time and in the meantime, the tariff pain would be operating. And of course there’s the question of whether any damages or remedies would be adequate.
We pointed out early on that China said it would file a WTO case against the latest Trump tariffs, but that amounted to a wet noodle lashing. The US and China off and on have filed WTO cases on various particularly infringements. I must confess I have not kept track of their resolution, but I have yet to read of an instance where they seemed to accomplish much (as in you’d expect Bloomberg or the Wall Street Journal or the Financial Times take note of a loss in a WTO suit that led to material changes in behavior). So even if there have been some actual remedies imposed, they do not seem to have had enough pain attached to them to affect behavior. With previous WTO cases involving Trump 1.0 tariffs where the WTO did not buy the the “emergency authorization” claim, the US simply ignored the court’s ruling.
The case of the Mexico and Canada tariffs (recall they have only been paused) would seem to be different than China, since each had signed the Trump-instigated United States–Mexico–Canada Agreement, which became effective in 2020 and replaced NAFTA. But that deal included provisions that strengthened the US ability to invoke emergency claims.
By Achyuth Anil, Researcher, Centre for Inclusive Trade Policy and Research Assistant in International Trade (Law) University Of Sussex. Originally published at VoxEU
President Trump accounted tariffs on imports from Canada, Mexico, and China on the basis of a “national emergency” in the form of the “extraordinary threat” posed to the US by “illegal aliens and drugs, including fentanyl”. This column examines the legal justification for the president’s actions and concludes that that (1) under US law, Trump’s tariffs are probably legal and very hard to challenge; and (2) internationally, the most countries might get from challenging the tariffs would be a symbolic victory. Realistically, negotiating with the US might be the only way to achieve practical results.
President Trump announced he would introduce tariffs on imports from Canada, Mexico, and China, supposedly on the grounds of holding the three countries responsible for the “extraordinary threat” posed to the US by “illegal aliens and drugs, including fentanyl” – something the president has declared as a national emergency. Following bilateral discussions with President Sheinbaum of Mexico and Premier Trudeau of Canada, Trump has since temporarily paused the imposition of the proposed tariffs against both countries, for one month. The 10% tariffs against China have been instated. There is no guarantee that the president will not reinstate the tariffs once again if he is not satisfied with Canada’s or Mexico’s promises, citing the same “national emergency”.
These proposed actions raise important legal issues, as well as economic consequences. In this column, I focus on the former. Under his first period as president (2017-2012), Trump also introduced tariffs on imports from China and others – but the legal basis was somewhat different. Section 301 of the Trade Act of 1974 and Section 232 of the Trade Expansion Act of 1962 were used for sweeping tariffs on Chinese-origin products and the tariffs on steel and aluminium products, respectively. This time round, Trump’s justification is that of a “national emergency”, under the International Emergency Economic Powers Act (IEEPA) passed in 1977. This raises the question of what constitutes a national emergency, and thus what is the basis for the president imposing these tariffs? What is the rationale and legal basis for imposing tariffs on maple syrup or avocados for alleged illegal fentanyl importation or illegal migration? Can such tariff measures be justified under international trade law?
Trump announced the tariffs on the basis of a “national emergency” declared under the National Emergencies Act (NEA), originally passed in 1976. The NEA provides a framework for the president to declare a national emergency. IEEPA is a statute under the umbrella of the NEA, which grants the president extensive powers to regulate a variety of international economic transactions during a state of national emergency. 1 Neither Act defines what constitutes a “national emergency”. Congress has practically no power to revoke a “national emergency” declared by the president, evidenced by the multiple national emergencies still in force in the US (Congressional Research Service 2021). These enormous and seemingly unchecked powers allow the president to declare a national emergency and simultaneously dictate how to regulate a variety of international economic transactions. There is scope for an aggrieved party in the US to take the tariff measure to a US court, raising the question of what constitutes a “national emergency”. However, the lack of a definition in either of the Acts lends itself to the idiosyncrasies of judicial interpretation. Previously the US Supreme Court has ruled deferentially on the president’s use of IEEPA. Therefore, it seems unlikely that a court will challenge the president’s determination of a “national emergency”.
Assuming a court in the US leaves it to the president to decide what constitutes a “national emergency”, the question still arises as to whether the presidential power to regulate international economic transactions include the power to impose tariffs during such an emergency? There is no answer to that question in the Act as it is silent in more ways than one. No president has previously used IEEPA to impose tariffs. In 1971, President Nixon did use the emergency powers under the predecessor to IEEPA, the Trading with the Enemy Act (TWEA), dating back to 1917, to impose 10% tariffs on all imports. The Nixon tariffs were challenged, and the court interpreted that the broad powers under TWEA allowed the president to regulate imports including through use of tariffs. IEEPA replaced TWEA and, although it is on similar lines as TWEA, there are differences between the two legislations and their application. Nevertheless, the courts have continued to use TWEA precedents to interpret IEEPA. It is therefore unclear whether the basis of differentiation between tariff imposition using national emergency justification under TWEA and IEEPA would lead to different conclusions. Some commentators argue that the tariffs against Canada, Mexico and China under IEEPA go beyond the scope of IEEPA (Harrell 2025). Others point out that the courts might not see it that way (Claussen 2025). On balance, it seems more likely that on the issue of the scope of IEEPA, the likely outcome of any challenge would be to favour the president.
In addition to the constitutional questions of the separation of powers, there are also legitimate questions as to how the imposition of tariffs actually relates to the emergency in question, and on this there is scope for the courts to intervene. A judge may leave it to the president to decide whether the alleged flow of drugs and illegal immigrants does constitute a national emergency. But a judge can theoretically, irrespective of the determination of existence of a “national emergency”, determine the appropriateness of any action undertaken in pursuance of the emergency. Hence, here the issue that could be ruled upon is the relation between the policy (the imposition of tariffs) and the stated goal of that action (to limit illegal immigration or drug smuggling). However, in practice courts have repeatedly rejected this argument that the use of IEEPA requires a direct link between the policy and the stated goal, or between the policy and the actions of a foreign country or national. In practice, it makes sense to punish maple syrup with tariffs as if maple syrup from Canada were the illegal drugs flowing into the US!
Table 1 President Trump’s trade actions on over broad domestic economy or national security considerations highlighting increasing use of powers that may be difficult to challenge
It would appear that the power the president utilised to impose tariffs under IEEPA is very nearly absolute and difficult to challenge. That might explain why the president chose this route instead of his 2018 route of Section 301 of the Trade Act of 1974 or Section 232 of the Trade Expansion Act of 1962, as previously. The Section 301 action requiresthe US Trade Representative make a finding that a foreign country is violating or denying US rights under a trade agreement or is engaged in unjustifiable conduct that burdens or restricts US commerce – a time-consuming process. Moreover, Section 301 tariffs are required to be terminated after four years unless an extension is requested and is approved. Similarly, Section 232 mandates the Department of Commerce to conduct an investigation and determine whether imports pose a threat to US national security. The president would also be unlikely to be able to announce or impose tariffs until the investigation were concluded. It does appear to be much simpler to declare a “national emergency” and impose sweeping tariffs on all products without any investigation from some countries than imposing tariffs on specific industry or sectors based on evidence.
But what about international law? Trump’s 2018 steel and aluminium tariffs on national security grounds were challenged at the WTO. The national security defence of those tariffs convinced no one at the WTO, with the panel finding that the situation at hand did not constitute an emergency in international relations and therefore, the tariffs were not justified under the security exception (Article XXI, GATT). Considering this panel decision, past rulings (Pinchis-Paulsen et al. 2024), and the conditions necessary to constitute an “emergency in international relations” as decided in such past rulings, it is unlikely that this February 2025 round of tariffs on products from Canada, Mexico, or China would be upheld by a WTO panel.
However, the US has consistently disagreed with this interpretation of the security exception, and effectively ignored the WTO ruling by appealing into the void. 2 It even revamped the security exception in the United States-Mexico-Canada Agreement (USMCA) to reflect its position on the issue. The USMCA security exception provision appears broader (Paine 2024) with language that gives parties more freedom to decide what they consider an essential security interest (Article 32.2), thereby limiting the possibility of a successful legal challenge by Canada or Mexico against any such US measures. Similar language is observed in security exception provisions in investment treaties and tribunals have interpreted such a provision narrowly to include only matters that is ‘absolutely necessary’ or ‘unavoidable’ to the state’s security agenda (Henckels 2024). However, the jurisprudence of such provisions in international investment law is different from the jurisprudence in international trade law. As of now, it is unclear how a USMCA tribunal might interpret this provision if either Canada or Mexico challenged the current US measure.
What can be done? Domestically in the US, it is possible to challenge and question the measure. But the law appears deliberately vague, and the past precedents favour the president, likely rendering any challenge futile. Internationally, Canada and Mexico can challenge this measure either under the WTO or the USMCA as the measure violates US commitments under both agreements. However, Canada and Mexico might have more success challenging this measure at the WTO than under the USMCA. Success might be too generous a term considering the crippled state of the WTO Appellate Body, thanks again to the US (Lester 2022). The fact is that even if a WTO panel rules against the US, the US can appeal into the void and the complaining parties will not be able to enforce the ruling. For China, the WTO is the sole avenue for raising a complaint and it wasted no time in doing just that. Legally, a WTO complaint might vindicate Canada, Mexico, or China.
Somewhat pessimistically, the conclusion appears to be (a) that under US law the ‘Trump tariffs’ are probably legal, and very hard to challenge; and (b) internationally at most countries might get a symbolic victory. Realistically, negotiating with the US might be the only way to achieve practical results, if one puts aside what it signals and the political ramifications of such an action. Getting the trading partner to the negotiating table indeed appears to be President Trump’s goal.
See original post for references
