The new Unified Patent Court (UPC) in Europe allows patent owners access to centralized enforcement, albeit at the risk of centralized invalidation. Moreover, patent owners will enjoy a large cost reduction for new unitary patents (UPs). With the introduction of the UPC/UP system in 2023, owners of existing European patents and patent applications could opt out of the new court system during a three-month time window. We derive a set of hypotheses and combine data on the opt-out decisions with a rich set of patent and owner characteristics to test them.