Celanese Int’l Corp. v. Int’l Trade Comm’n
Authored by: Jeremy J. Gustrowsky
In a significant decision for patent owners and applicants, the Federal Circuit has reaffirmed that selling products made by a secret process before filing for a patent can still invalidate later patent claims on that process—even under the America Invents Act (AIA). This case involved Celanese International Corporation, which had developed a secret process for making the artificial sweetener Ace-K. Celanese sold Ace-K made by this process in the United States more than a year before filing for patents covering the process (U.S. Patent Nos. 10,023,546; 10,208,004; and 10,590,095). When Celanese tried to enforce these patents, the International Trade Commission found them invalid under the “on-sale bar,” and the Federal Circuit has now affirmed that decision.
Celanese argued that the AIA, which updated U.S. patent law in 2011, changed the rules so that only public sales or disclosures would trigger the on-sale bar, not secret sales of products made by a hidden process. The company pointed to new language in the law, such as the reference to the “claimed invention” and the phrase “otherwise available to the public,” as evidence that Congress intended to narrow the on-sale bar. However, the court disagreed, finding that Congress did not intend to overturn long-standing precedent that secret commercial sales can still bar a patent.
The Federal Circuit relied heavily on the Supreme Court’s 2019 Helsinn decision, which held that the AIA did not fundamentally change the meaning of “on sale” in the patent statute. The court explained that the purpose of the on-sale bar is to prevent inventors from commercially exploiting their inventions for more than a year before seeking patent protection. Allowing secret sales to escape the bar would undermine this policy, letting inventors extend their monopoly beyond the intended patent term.
For inventors and companies, this decision is a clear reminder: if you sell products made by a new process—even if you keep the process itself secret—those sales can prevent you from later patenting the process if you wait more than a year to file. The AIA did not create a loophole for secret commercial activity, and the traditional on-sale bar remains firmly in place.