Patent portfolios often span multiple related entities – a parent corporation and its subsidiaries, spinouts, or partners. When patent applications share overlapping subject matter, a US Patent Examiner may raise an obviousness type double patenting (ODP) rejection. The usual fix, a terminal disclaimer (TD) pursuant to common ownership, is not available when the patents are owned by different entities. This can have very real effects when a parent company assigns some patent applications in a portfolio, such as application-focused patents, to one wholly owned subsidiary while other foundational patents remain with another wholly owned subsidiary. IP attorneys Grant Ehrlich and Kim Vines take a look at double patenting and more in this Stites & Harbison Client Alert.