The Unified Patent Court (UPC) has played an increasingly prominent role in European patent enforcement since its launch one year ago. Its broad jurisdiction offers key advantages to patent owners, allowing them to target infringement across 17 participating European Union (EU) member states in a single complaint—including claims over both traditional European patents (EPs) as well as the newly created European patents with unitary effect, or unitary patents. However, the court also allows companies to file similarly sweeping revocation actions, leading some patent owners to opt some of their EPs out of the court’s jurisdiction (as permitted during an initial seven-year transitional period) to protect those assets from invalidation before the UPC. Such opt-outs can fail, though, if all rights-holders are not accounted for, according to a recent decision by the UPC Court of Appeals—creating a potential pitfall for patent owners that have spread the ownership rights to their assets among multiple holding companies.