Not to be confused with patents relating to submarines (in any sense).
A submarine patent is a patent whose issuance and publication are intentionally delayed by the applicant for a long time, which can be several years, or a decade.[1][2][3] This strategy requires a patent system where, first, patent applications are not published, and, second, patent term is measured from grant date, not from priority or filing date. In the United States, patent applications filed before November 2000 were not published and remained secret until they were granted. Analogous to a submarine, submarine patents could remain "under water" for long periods until they "emerged", surprising the relevant market. Persons or companies making use of submarine patents are sometimes referred to as patent pirates.[4][5]