A practitioner’s guide to the USTR Section 301 investigations launched 11 March 2026 – and what they mean for British companies manufacturing in or sourcing from the 16 investigated economies.
On 11 March 2026, the US Trade Representative (USTR) formally initiated Section 301 investigations against 16 major economies — China, the European Union, Japan, South Korea, Vietnam, Mexico, India, Taiwan, Singapore, Malaysia, Thailand, Indonesia, Switzerland, Norway, Bangladesh, and Cambodia. The investigations target what Washington terms ‘structural excess capacity and production in manufacturing sectors’: government-subsidised overproduction that floods global markets, depresses prices, and displaces US domestic industry.
This is not routine trade process. Section 301 is one of the most powerful and legally durable instruments in US trade law. Its use here represents a deliberate and strategic pivot away from the IEEPA-based tariff executive orders recently struck down by the Supreme Court. Unlike those emergency orders, Section 301 investigations follow a structured process — public comment, hearings, findings — that creates an administrative record making resulting tariffs extremely difficult to challenge in court.
For UK and EU businesses, the implications are immediate and material, whether or not your company exports directly to the United States.
What Section 301 Actually Means
Section 301 of the Trade Act of 1974 authorises the US Trade Representative to investigate whether foreign government acts, policies, and practices are ‘unreasonable or discriminatory’ and burden or restrict US commerce. If the investigation concludes affirmatively, the USTR must determine what action to take. That action can include:
- Tariffs and additional duties on imports from investigated economies
- Investment restrictions and screening requirements
- Export controls on US goods and technology
- WTO dispute settlement proceedings
- Restrictions on intellectual property licensing and market access
The first Trump-era Section 301 investigation against China in 2018 produced tariffs that remain in force today. The legal architecture is intentionally robust. This is not a temporary lever; it is structural trade policy that, once enacted, persists across administrations.
My clients report that tariff unpredictability proves more destructive than tariffs themselves, preventing long-term investment decisions essential for growth. The Section 301 process now underway will, if it proceeds to findings, produce duties that are far harder to unwind than anything imposed under emergency executive authority.
Douglas Mackay – ITM Specialist
The 16 Investigated Economies: Sectors in the Crosshairs
USTR has published detailed evidence of structural excess capacity for each of the 16 economies. The table below maps each investigated economy to the key sectors identified in the Federal Register Notice (Docket No. USTR-2026-0067):
| Economy | Key Surplus Sectors Under Investigation |
| China | Electronic equipment, machinery, automobiles & auto parts, steel, plastics, furniture, apparel, chemicals, aluminium, ships |
| European Union | Chemicals, machinery, vehicles; Germany: autos, machinery, pharma; Ireland: pharmaceuticals |
| Japan | Automobiles & auto parts, optical/medical apparatus |
| South Korea | Electronic equipment, autos & parts, machinery, steel, ships & marine vessels |
| Vietnam | Electronic equipment, machinery, footwear, apparel, furniture, steel (also final assembly hub) |
| Mexico | Automotive sector (79.7% of exports to US), construction, rail & ship transportation, food & beverages |
| India | Textiles, health, construction goods, automotive, solar modules, petrochemicals |
| Taiwan | Semiconductors, electronic products, IT products, machinery |
| Singapore | Semiconductors, electronic equipment, petrochemicals, pharmaceuticals |
| Malaysia | Electronic equipment, mineral fuels, machinery, medical apparatus, steel |
| Thailand | Autos & auto parts, machinery, rubber |
| Indonesia | Metals, agricultural products, fuels, textiles, construction goods |
| Switzerland | Refined gold, pharmaceutical products, organic chemicals, machinery |
| Norway | Mineral fuels & oils, electronic equipment, machinery, seafood |
| Bangladesh | Textiles & garments, footwear, leather goods |
| Cambodia | Garments, footwear, travel goods |
An illustrative list of sectors USTR considers systemically affected across multiple economies includes: aluminium, automobiles, batteries, cement, chemicals, electronics, energy goods, glass, machine tools, machinery, non-ferrous metals, paper, plastics, processed food and beverages, robotics, satellites, semiconductors, ships, solar modules, steel, and transportation equipment.
What This Means for UK Companies
The United Kingdom is not named in this round of investigations. That is welcome, but it does not represent a clean bill of health. British businesses face three distinct categories of risk that require immediate assessment.
1. Supply Chain and Manufacturing Exposure
UK manufacturers that produce goods in — or source components, materials, or sub-assemblies from — any of the 16 investigated economies are directly inside the risk perimeter. If tariffs are imposed on those goods entering the United States, the economics of your supply chain change fundamentally. Companies that have implemented China-plus-one diversification strategies through Vietnam, Mexico, or India now find those alternative sources are themselves under investigation.
Affected sectors of particular relevance to UK manufacturers and their supply chains include: automotive and auto parts, electronics and semiconductors, pharmaceuticals and chemicals, steel and aluminium, textiles and apparel, and machinery.
2. Trade Diversion Risk
When goods are blocked — or made uncompetitive — in the US market, they seek new destinations. UK manufacturers and retailers could face a surge of competitively priced imports from investigated economies flowing into domestic and EU markets. For sectors where UK industry already competes on thin margins — steel, aluminium, automotive components, electronics, textiles — this is a material competitive threat.
3. Transshipment and Compliance Risk
USTR explicitly notes that some investigated economies ‘export their excess capacity and production by establishing distribution and production networks in other countries.’ This is the transshipment risk that UK exporters to the US must actively manage. US Customs enforcement of origin rules is intensifying. Goods that are processed or assembled in the UK using components or materials that originate substantially in investigated economies may face scrutiny — particularly if the UK is perceived as a low-tariff gateway.
| Action Required: Transshipment Review UK exporters to the United States should urgently review their rules of origin positions for goods containing inputs from any of the 16 investigated economies. This is especially critical for companies in electronics, automotive, pharmaceuticals, steel products, and textiles. International Trade Matters can provide a supply chain origin audit to identify and mitigate this risk. |
The USTR Comment Process: Why UK and EU Companies Should Engage
USTR has opened a public comment process. This is not bureaucratic formality — it is an evidentiary proceeding that will directly shape findings. The administrative record built through comments and hearings forms the legal foundation for any subsequent tariff action. Companies that engage with evidence have the ability to influence both the scope and the targeting of any resulting measures.
USTR specifically invites submissions on:
- Whether the industrial policies and practices of each investigated economy create or maintain structural excess capacity in specific sectors
- Whether those practices are unreasonable or discriminatory
- Whether and how those practices burden or restrict US commerce — including quantitative economic assessments
- Whether and what tariff or non-tariff action should be taken
- Additional considerations relevant to the assessment of structural excess capacity
For UK and EU companies with manufacturing or sourcing operations in investigated economies, a well-evidenced submission can present data showing that your specific operations do not involve government-subsidised overproduction, that production levels reflect genuine market demand, and that capacity utilisation in your sector aligns with or exceeds international benchmarks. This is particularly relevant for EU-based manufacturers and for UK companies with EU supply chain partners.
Key Deadlines
| Date | Milestone |
| 11 March 2026 | Investigations formally initiated by USTR Ambassador Jamieson Greer |
| 17 March 2026 | USTR dockets open for written submissions (portal: comments.ustr.gov) |
| 15 April 2026 | DEADLINE — written comments and requests to appear at hearings (11:59 pm EST) |
| 5–8 May 2026 | Public hearings convene at US International Trade Commission, Washington DC |
| ~15 May 2026 | Post-hearing rebuttal comments due (7 days after last hearing day) |
| Before July 2026 | Expected findings — timed to Section 122 interim tariff expiry |
Submissions must be made through the USTR online portal at https://comments.ustr.gov/s/ under Docket No. USTR-2026-0067. Business confidential information may be submitted and protected from public disclosure if properly designated.
The Broader Strategic Context
It is important to understand this investigation in its wider strategic context. Global manufacturing capacity utilisation stands at approximately 75–76%, below the 80% threshold economists consider healthy. China alone accounted for nearly 70% of global goods trade surpluses in 2025, with a record $1.2 trillion surplus. The UNIDO Quarterly Report on Manufacturing Production and Trade confirms that China, Asia and Oceania, and Europe have consistently run surpluses in manufactured goods — while North America has run growing deficits.
From a US policy perspective, this is not merely about excess capacity. The investigation list closely mirrors the list of countries with which the US runs the largest bilateral goods deficits. Washington’s strategic objective is to rebuild domestic manufacturing capacity and supply chain resilience — a goal that cuts across administrations and commands bipartisan support in Congress.
For British companies, the post-Brexit context adds a further layer of complexity. UK manufacturers have already navigated EU trade barriers, supply chain disruptions, and the partial reconfiguration of transatlantic commercial relationships. American tariff instability — now operating through a legally robust mechanism — adds another material variable to planning that was already difficult.
Trust, like supply chains, is easier destroyed than rebuilt. The question for British businesses is not whether to engage with this process, but how to engage effectively — and what strategic adjustments to make regardless of the outcome.
Recommended Immediate Actions for UK and EU Businesses
- Map your supply chain exposure. Identify all suppliers, sub-suppliers, and manufacturing partners across the 16 investigated economies. Prioritise electronics, automotive, pharmaceuticals, steel, and textiles.
- Conduct an origin compliance review. Assess rules of origin for goods you export to or import from the US. Identify any transshipment risk arising from inputs from investigated economies.
- Assess trade diversion risk to your UK or EU market positions. Model what happens to your competitive position if underpriced goods, displaced from the US market, flow into your domestic markets.
- Consider whether to make a submission to USTR. If your business has operations or sourcing relationships in investigated economies, a well-structured comment can meaningfully influence the scope of any measures. The deadline is 15 April 2026.
- Monitor the investigation progress. Findings are expected before July 2026. Early preparation of contingency scenarios — alternative sourcing, pricing adjustments, contractual protections — is essential.
- Seek specialist guidance. The interaction between Section 301, UK/EU trade agreements, and rules of origin is complex. International Trade Matters can provide tailored analysis and assist with USTR submissions.
How International Trade Matters Can Help
Our team of experienced international trade specialists can assist UK and EU businesses with: supply chain origin audits; risk assessment across the 16 investigated economies; preparation and submission of USTR public comments and hearing representations; scenario planning and contingency strategy; and ongoing monitoring of investigation developments.
Contact us on+44 (0) 333 7722 565 or info@internationaltradematters.com
