On March 11, 2026, the US Trade Representative (USTR) has launched a fresh round of Section 301 trade investigations targeting the policies and industrial practices of 16 economies.This marks a significant escalation in trade scrutiny at a time when Washington’s earlier tariff strategy has been outlawed by a US Supreme Court ruling.Countries included are: China, the European Union, Singapore, Switzerland, Norway, Indonesia, Malaysia, Cambodia, Thailand, South Korea, Vietnam, Taiwan, Bangladesh, Mexico, Japan and India. The probe covers sectors including steel, aluminium, automobiles, batteries, electronics, chemicals, machinery, semiconductors and solar modules.IndiaThe US investigation identifies several sectors in India where structural excess capacity or export surpluses may exist. These include solar modules, petrochemicals, steel, textiles, health-related goods, construction materials and automotive products.According to the US notice, India’s solar-module manufacturing capacity is already nearly three times domestic demand, suggesting the possibility of export-driven production surpluses. Similar concerns are raised about expanding capacity in petrochemicals and steel.Investigation processUnder Section 301 of the US Trade Act of 1974, the US government may investigate whether foreign trade practices are unreasonable or discriminatory and harm American commerce. The investigations will examine whether policies such as industrial subsidies, state-supported manufacturing expansion, activities of state-owned enterprises, market-access barriers, currency practices or suppressed domestic demand have contributed to global manufacturing overcapacity that burdens US commerce.If such practices are confirmed, Washington may impose retaliatory trade measures, including additional tariffs, quantitative restrictions or other trade barriers.The investigation will follow a defined process. Public dockets for written submissions will open on March 17, 2026, allowing companies, trade groups and governments to submit comments. Written submissions and requests to participate in hearings must be filed by April 15. Public hearings will take place from May 5 to May 8 at the US International Trade Commission in Washington. Rebuttal submissions must be filed within seven days after the hearings conclude. After consultations with the governments concerned, the USTR will determine whether the practices under investigation warrant retaliatory action.Background: Tariff strategy collapseThe launch of these investigations comes just 20 days after a major legal setback for the Trump administration’s trade strategy. On February 20, 2026, the US Supreme Court struck down the legal basis for the administration’s “reciprocal tariffs,” which had been used to pressure trading partners into making concessions in trade negotiations.Within hours of the ruling, Washington imposed a uniform 10% tariff under Section 122 of the Trade Act of 1974, replacing targeted tariff pressure with a flat duty applied to all countries.However, the shift created a new dilemma for the United States. Several countries had already negotiated trade arrangements with Washington under the earlier tariff framework. These agreements included higher negotiated tariff levels – around 15% for the European Union, Japan and South Korea, about 20% for Vietnam and Taiwan, and roughly 19% for Indonesia and Thailand.After the court ruling introduced a universal 10% tariff, those negotiated advantages effectively disappeared, prompting some governments to reconsider the value of trade deals with US.Many of the countries now facing Section 301 investigations had already concluded some form of trade agreement or framework arrangement with the United States after April 2025. These include the European Union, Indonesia, Japan, Malaysia, Cambodia, South Korea, Vietnam, Taiwan and Bangladesh. China operates under a temporary tariff arrangement, while Singapore, Switzerland, Norway, Thailand, Mexico and India remain in negotiations.India, for example, signed a joint statement with the United States on February 6, 2026, committing to reduce tariffs on many goods, purchase more than $500 billion of US products over five years, ease digital regulations affecting American technology firms and relax certain regulatory barriers for US exports.US President Donald Trump has warned trading partners against attempting to renegotiate these arrangements. Global Trade Research Institute (GTRI) notes that while Section 301 remains an important US trade tool, it is slower and more legally constrained than the reciprocal tariff system invalidated by the Supreme Court. Section 301 investigations require evidence of harm and must be tied to specific trade practices.The United States may also consider tariffs under Section 232 of the Trade Expansion Act of 1962, which allows trade restrictions on national-security grounds. The provision has already been used to impose high duties on steel and aluminium and could potentially be extended to additional sectors.The revival of Section 301 investigations signals that US trade policy is entering a new phase following the court ruling that curtailed Washington’s tariff powers.With its earlier tariff strategy effectively dismantled, the United States appears to be turning to trade investigations and targeted measures to maintain leverage in negotiations with trading partners. Ajay Srivastava is the founder of Global Trade Research Institute (GTRI).