IP Law Daily, PATENT NEWS—High Court declines Celanese’s bid to narrow scope of on-sale bar for process patents, (May 1, 2025)

By Saurabh Kashyap, B.A., LL.B., LL.M.

Certiorari denial leaves intact Federal Circuit’s ruling that secret commercial sales of end products can trigger § 102(a)(1) and invalidate process patents.

The U.S. Supreme Court has declined to hear Celanese International Corporation’s challenge to the Federal Circuit’s interpretation of the on-sale bar under the America Invents Act (AIA), leaving undisturbed a ruling that invalidated Celanese’s process patents for manufacturing acesulfame potassium (Ace-K). The denial of Celanese’s petition for certiorari lets stand the Federal Circuit’s holding that commercial sales of products made by undisclosed patented processes can trigger the on-sale bar under 35 U.S.C. § 102(a)(1), even when the process itself is not disclosed (Celanese International Corp. v. International Trade Commission, Dkt. No. 24-635.

Background. Celanese International Corporation, along with its affiliates Celanese (Malta) Company 2 Limited and Celanese Sales U.S. Ltd., specializes in manufacturing chemicals and proprietary processes, including patented methods for making Ace-K, a popular artificial sweetener. The dispute arose after Celanese filed a Section 337 complaint with the International Trade Commission (ITC), alleging that Anhui Jinhe Industrial Co., Ltd. and Jinhe USA LLC imported Ace-K made using Celanese’s patented processes.

The asserted patents were U.S. Patent Nos. 10,166,247 (the ’247 patent) and 10,233,163 (the ’163 patent), covering processes designed to improve the yield and environmental performance of Ace-K production. Celanese sought to block Jinhe’s imports, alleging infringement of these process patents.

The on-sale bar argument. Jinhe moved for summary judgment, contending that Ace-K made using Celanese's patented processes had been sold in the United States more than a year before Celanese's patent applications were filed, triggering the AIA's on-sale bar. Jinhe did not argue that the patented processes were disclosed or reverse-engineerable from the Ace-K sold but asserted that the sale of the end product alone invalidated the patents.

Celanese responded that its patented processes—the "claimed invention"—had never been sold or made public and that § 102(a)(1), as revised by the AIA, barred patents only when the invention itself was on sale. Celanese argued that the AIA's adoption of the term "claimed invention" and the addition of "otherwise available to the public" narrowed the on-sale bar to exclude undisclosed processes.

ITC and Federal Circuit rulings. The ITC’s administrative law judge granted summary judgment of invalidity, relying on pre-AIA case law, including D.L. Auld v. Chroma Graphics Corp., 714 F.2d 1144 (Fed. Cir. 1983), which held that sales of products made using secret processes could invoke the on-sale bar. The ITC declined to review the ruling.

On appeal, the Federal Circuit affirmed. In Celanese International Corp. v. ITC, No. 22-1827 (Fed. Cir. 2024), the panel held that Congress's use of similar language in the AIA indicated no intent to change the long-standing rule that selling products made by secret processes could bar patentability. Citing Helsinn Healthcare S.A. v. Teva Pharmaceuticals USA, Inc., 586 U.S. 123 (2019), the court confirmed that even confidential sales can trigger the on-sale bar, concluding that Ace-K sales fell within the statutory bar even though the patented processes were undisclosed.

Celanese’s Supreme Court petition. Celanese petitioned for certiorari in December 2024, contending that the Federal Circuit misread the AIA. The company argued that the statute’s reference to the “claimed invention” means the invention as defined by the patent claims—in this case, processes for making Ace-K—and that sales of a product made using a secret process do not amount to a sale of the invention itself. Celanese asserted that the AIA’s textual changes were intended to narrow the scope of the on-sale bar and align U.S. law with global norms that protect undisclosed processes from invalidation by sales of end products.

Celanese also maintained that the Federal Circuit’s reliance on Helsinn was misplaced because that case involved confidential sales of a product patent, not a process patent. Celanese warned that applying Helsinn’s reasoning to process patents created legal uncertainty, discouraging innovation in industries where process patents are essential.

Denial of review. The Supreme Court denied certiorari without comment, letting the Federal Circuit’s ruling stand. The denial leaves unresolved Celanese’s core contention that the AIA should be interpreted to exclude undisclosed processes from the on-sale bar’s reach.

The Case is Dkt. No. 24-635.

News: Patent FedCirNews