On April 28, 2025, the U.S. Supreme Court declined to hear Celanese International Corp.’s challenge to a Federal Circuit decision which found the company’s patent on the process to create the artificial sweetener used in Coke Zero to be invalid. The Federal Circuit decision affirmed a holding from the U.S. International Trade Commission which initially deemed the patent invalid due to the on-sale bar.

The underlying issue in the case is whether Celanese’s patent, which covers an improved process for making acesulfame potassium (Ace-K), was invalid due to the on-sale bar. The ...