Submarine Patents

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Years ago, so-called submarine patents could torpedo good faith efforts of inventors and their companies. Such hidden patents came about because the USPTO dated a patent application – the application filing date – and approximately two years later the USPTO assigned the application a patent number – the issue date.

The inventor had no rights from the date of filing to the date of issue. However, once the patent number was issued, the inventor was given 17 years time window to enforce the patent rights. Moreover, during the “patent pending” stage, the invention was kept confidential by the USPTO and was not disclosed. During the prosecution of the patent, the inventor was allowed to modify his application any number of times, a powerful right indeed!

The inventor could tweak the specifications and claims in his application to better match emerging industry standards. Alternatively, the
inventor could file continuation applications, which retained the earliest filing date. One day, the submarine patent, unknown to the world, emerged with 17 years left of enforcible life. Companies which had manufactured products based on the patents challenged by the submarine patent would be forced to cough up big royalties.

Jerome Lemelson amassed close to $1.5 billion because he kept his 1960s patents alive for 30 years by means of reexaminations, rejections and resubmissions. For example, his inventions related to machine reading and bar coding initially asserted very broad claims. Over the decades, the claims were rejected and he split the invention into parts and narrowed and refined the invention and filed for examination again and again as he incorporated technological developments in the refinements. He also filed continuation applications in accordance with ongoing developments.

Once the underground patents issued in 1990s, Lemelson launched lawsuits against Ford, General Motors, Chrysler, Sony and many other giant corporations, nearly all of whom settled, until the lucrative game ended with a court ruling against the Lemelson Foundation.

By simply amending the patent application for minor changes, inventors could keep their patents alive almost indefinitely in the USPTO. Gilbert P. Hyatt obtained a patent on an invention related to a single sip microcontroller in 1990. The patent was filed way back in 1970. Texas Instruments applied and obtained a patent based on similar lines between 1970 and 1990 and made products based on its patent.  When the Hyatt patent emerged, it invalidated the patent obtained by Texas Instruments claiming an earlier filing date. By 1992 Hyatt had collected $70 million in royalties, until four years later a court overturned Hyatt‘s patent.

Reforms Limited Patent Terms and Secrecy

The outcry against submarine patents led to a series of statutory and decision reforms. According to a 1995 law, for any application filed
after June 8, 1995, the term begins on the issue date and extends for a period ending twenty years from the effective filing date. This prevented inventors from keeping their patents alive for decades.

For applications pending in the Patent Office as of June 8, 1995, or in force as of that date, the patent term runs for the greater of the time period of seventeen years from the patent issue date or twenty years from the effective filing date. Having sunk submarines going forward, the ones filed before the reforms still have an advantage.   So care has to be taken while dealing with patent applications filed before the 1995 reforms.

Before the Patent Act of 1999, patent applications were kept secret and the subject matter undisclosed until the patent number was allotted to the application. The 1999 patent reforms remove this secrecy.  All applications filed after the reform are published within 18 months of filing. This allows companies to take preemptive measures to avoid infringement or to
work around the invention.   Finally, an influential Court of Appeals decision held that a patent applicant’s unreasonable delay in prosecuting its application to issuance violated the equitable doctrine of laches and rendered the patent unenforceable.

(Featured image source:

Rahul Vijh
Rahul Vijh

There is nothing permanent except change. And it’s that change that Rahul enjoys blogging about. Whether it is the latest change to patent law, or the biggest, newest, latest device on the market, Rahul is sure to be up to date with the story, the background and the future.


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