ancillary to priority. Patents. An issue that is so logically related to the issue of priority of invention that it cannot be separated from the issue of priority. • The question whether an issue is ancillary to priority was once used to challenge the jurisdiction of the U.S. Patent and Trademark Office, but the Board of Patent Appeals and Interferences now has explicit jurisdiction over ancillary issues. [Cases: Patents 90(1). C.J.S. Patents §§ 120–122.]