Double Patenting: The Ticking Time Bomb


Changes in patent term calculation have outpaced the law of double patenting in the US, leaving the validity of some issued patents in question, warns David Halstead....

Obviousness-type double patenting (OTDP) is a rare beast in the realm of patent law. In a regime dominated by statutes and rules, OTDP arises from equity. Like patent misuse, implied licence and the doctrine of equivalents, OTDP was judicially created to right perceived wrongs allowed by those statutes and rules.

One of the underlying wrongs is unjust extension of patent term. OTDP law was created when US patents lasted 17 years from their issue date. Routine practices like filing a continuation application and pursuing additional claims to an invention could have been used to effectively extend patent term indefinitely. But requiring a terminal disclaimer (TD) in subsequent applications that claim patentably indistinct inventions eliminates this possibility.

The second, less obvious wrong is the risk that an infringer would be subject to multiple lawsuits with different parties on patents arising out of the same inventive activities. Such duplicative lawsuits unfairly increase the risk for potential infringers and deter competition, so multiple patents to essentially the same invention should not be separated from each other.

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DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.

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