Causes
| "Prior to requiring the publication of applications, the public would not learn of a patent until after it issued, which is often several years after the application was filed. Some patentees took advantage of this practice to the extreme (with ‘‘submarine’’ patents), and intentionally delayed their patents issuance, and thus publication, of the patent for several years to allow potentially infringing industries to develop and expand, having no way to learn of the pending application." |
| —U.S. Committee on the Judiciary, 2008 |
Submarine patent practice was possible previously under the United States patent law, but is no longer practical since the U.S. signed the TRIPS agreement of the WTO: since 1995, patent terms (20 years in the U.S.) are measured from the original filing or priority date, and not the date of issuance. A few potential submarine patents may result from pre-1995 filings that have yet to be granted and may remain unpublished until issuance. Submarine patents are considered by some, including the US Federal Courts, as a procedural laches (a delay in enforcing one's rights, which may cause the rights to be lost).
In the past, when the life of a U.S. patent was 17 years from the date it was granted, submarine patents could issue decades after the initial filing date. Therefore, an applicant for a U.S. patent could benefit by delaying the issuance, and thus expiration date, of a patent through the simple, but relatively costly, expedient of filing a succession of continuation applications. Some submarine patents emerged as much as 40 years after the date of filing of the corresponding application. During the extended prosecution period the claims of the patent could be tweaked to more closely match whatever technology or products had become the industry standard.
Currently, the majority of U.S. patent applications are published within 18 months after the filing date. However, the applicant can explicitly certify that they do not intend to file a corresponding patent outside the U.S. at the time they file the patent, and keep the application secret. The applicant can change their mind within the first year, but the application is then published. For continuation applications which claim priority to a previously filed application, the publication is six months after the new filing date. The changes to U.S. patent law that introduced publication at 18 months also changed the duration of the patent to 20 years from the filing date of the earliest patent application in any chain of continuation patent applications. As a result there is little benefit in postponing the grant of the patent. The enforceable life of the patent can no longer be shifted into the period when a technology has become more widely adopted, and the patent applicant must give up the chance of foreign patent protection if he is to maintain patent secrecy beyond the 18 month period. In a recent report the National Academy of Sciences has recommended that "in all cases, applications should be published during patent examinations".
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