Why it matters:

On 20 February 2026, the US Supreme Court ruled that a wide range of tariffs imposed by President Trump in 2025 were unlawful. The ruling makes it more difficult for the US to impose tariffs more or less "at will", although it's unlikely to turn the clock back to the lower tariff environment of the pre-Trump era (indeed, Trump responded by responding an across-the-board minimum tariff of 10% under a different statute). More widely, it signals that – at least on some issues - the US Supreme Court is not prepared to defer to the Executive branch. For more detail, read What does the US Supreme Court's tariff ruling mean for exporters to the US?

Our view:

Whilst the ruling raises the prospect of refunds for some (read on for more), in the short to medium term, it creates further unwelcome uncertainty for business. For example, it's unclear whether President Trump's threat to impose an across-the-board tariff of 15% (rather than the current 10%) will be followed through. In addition, there remains a lack of clarity over the status of recently negotiated trade agreements with the US (for example, will certain goods from certain countries be exempt from the 10% tariff?). In the longer term, however, the ruling is likely to act as a constraining influence on US tariff policy – although it may be that other factors, such as the Middle East conflict and the US mid-terms, will prove equally, if not more, constraining in practice.