Supreme Court Declines to Hear China Section 301 Tariff Challenge, Bringing Long-Running Litigation to a Close

On June 15, 2026, the U.S. Supreme Court denied a petition for certiorari in HMTX Industries, LLC, et al. v. United States, the lead case challenging the legality of the Section 301 tariffs imposed on imports from China under Lists 3 and 4A. The Court’s decision leaves intact prior rulings from both the U.S. Court of International Trade (CIT) and the U.S. Court of Appeals for the Federal Circuit, which upheld the tariffs and the authority of the Office of the United States Trade Representative (USTR) to impose them.

For the thousands of importers that participated in the litigation, the Supreme Court’s decision marks the end of one of the most significant customs and trade disputes in recent history.

Background of the Litigation

The Section 301 tariffs originated from the USTR’s investigation into China’s acts, policies, and practices related to technology transfer, intellectual property, and innovation. Following that investigation, the United States imposed additional duties on hundreds of billions of dollars’ worth of Chinese-origin goods through a series of tariff lists.

While the initial Lists 1 and 2 tariffs were generally not challenged, Lists 3 and 4A became the focus of extensive litigation. Thousands of importers argued that USTR exceeded its statutory authority when it expanded the tariff measures beyond the original actions announced during the investigation.

Beginning in 2020, more than 6,000 importers joined the litigation, seeking refunds of duties paid and challenging the validity of the additional tariffs. The cases were consolidated and largely stayed pending resolution of the lead action brought by HMTX Industries and other plaintiffs.

Courts Consistently Upheld the Tariffs

The Court of International Trade ruled that USTR acted within its authority when it modified its original Section 301 action to include Lists 3 and 4A. The Federal Circuit subsequently affirmed that decision, concluding that the agency’s actions were authorized under the Trade Act of 1974 and were not inconsistent with the statutory framework governing Section 301 actions.

The plaintiffs sought Supreme Court review, hoping to overturn those decisions and obtain refunds of duties paid under the challenged tariff lists. However, the Supreme Court declined to hear the case and provided no explanation for its decision, which is common practice when denying certiorari petitions.

What Happens Next?

With the Supreme Court declining review, the legal challenge has effectively reached its conclusion. The Federal Circuit’s decision remains controlling, and the Section 301 tariffs imposed under Lists 3 and 4A remain valid and enforceable.

The Court of International Trade is expected to establish procedures for dismissing the thousands of stayed cases that were awaiting the outcome of the lead litigation. Importers that participated in those actions should anticipate further procedural guidance from the court regarding the disposition of their claims.

For most participants, the dismissal of the stayed cases will likely end any remaining opportunity to pursue refunds based on the arguments advanced in the litigation.

Practical Implications for Importers

The Supreme Court’s decision provides long-awaited certainty regarding the legality of the China Section 301 tariffs. Although many importers hoped the litigation would ultimately result in duty refunds, the denial of certiorari confirms that the courts will not disturb the existing tariff framework through this challenge.

Importers should continue to account for applicable Section 301 duties in their sourcing, pricing, and customs compliance strategies. Companies that have relied on the possibility of future refunds may need to reassess financial reserves, duty exposure, and long-term supply chain planning.

The decision also underscores the importance of exploring alternative duty mitigation strategies, including tariff engineering, first-sale valuation where appropriate, foreign trade zones, duty drawback opportunities, and country-of-origin planning, rather than relying on litigation outcomes to reduce duty liability.

Looking Ahead

Although this chapter of the China Section 301 litigation appears to be closed, trade policy remains highly dynamic. Importers continue to face evolving tariff programs, forced labor enforcement initiatives, antidumping and countervailing duty proceedings, and new Section 301 investigations in other areas. As a result, proactive customs and trade compliance planning remains essential.

For businesses that imported Chinese-origin merchandise subject to Lists 3 and 4A, the Supreme Court’s decision provides finality—even if it is not the outcome many had hoped for. The focus now shifts from litigation to managing ongoing tariff exposure and identifying practical strategies for reducing customs costs moving forward.

Companies affected by Section 301 duties should evaluate whether alternative customs and trade strategies may help mitigate duty exposure and strengthen supply chain resilience. Liang + Mooney PLLC assists importers with customs compliance, tariff mitigation strategies, Section 301 matters, duty drawback, origin determinations, and customs litigation. If you have questions about how this decision affects your business or would like to explore available options, contact our team to schedule a consultation.

Disclaimer: This article is provided for informational purposes only and does not constitute legal advice; readers should consult qualified counsel regarding their specific circumstances.