Prosecution history key to patent infringement actions

By TS Sharat, Clairvolex Knowledge Processes

As an integral aspect of patent portfolio management, big corporations and Fortune 100 companies have developed internal strategies to commercialize IP globally.

Such strategies lay emphasis on the decision making phase pertaining to the filing and prosecution of a given patent application in countries of interest. Patent activity is typically believed to commence from the research and development cell of a company. A company’s inventions may become prospective patents.

With the commencement of patent activity, the product or service embodying the invention is described through manuals or product catalogues. Alternatively, a white paper is published after the patent application has been filed.

TS Sharat Engineer Clairvolex Knowledge Processes
TS Sharat
Clairvolex Knowledge Processes

It has also become a common practice to file a patent application in a number of countries besides the country of origin, for reasons that are predominantly commercial. Each of these patent applications is pursued with the regional patent offices and often results in extensive foreign prosecution history.

Regional patent offices conduct searches to apply substantive rejections to the claimed invention. Some offices, such as the US Patent and Trademark Office (USPTO), mandate the submission of foreign prosecution details, such as cited arts or references, if any, and a grant status, etc., during the prosecution of a foreign patent application.

A well known impact of prosecution history on a patent in the US is typically referred to as “prosecution history estoppel” or “file wrapper estoppel”. In essence, prosecution history estoppel completely prohibits patent owners from asserting the “doctrine of equivalents” for certain elements of claims in instances where, during patent prosecutions, the following are filed: (i) an amendment that narrows the scope of a claim for reasons related to statutory requirements for a patent; (ii) a “voluntary” claim amendment that narrows the scope of the claim for reasons related to statutory requirements for a patent; (iii) an amendment and fails to explain the reasons for the amendment during prosecution of a patent; and (iv) an argument that narrows the interpretation of a claim element.

The doctrine of equivalents is a legal rule followed by most of the patent systems in the world. It allows a court to hold a party liable for patent infringement, even though the infringing device or process does not fall within the literal scope of a patent claim, but nevertheless is equivalent to the claimed invention.

Hence, prosecution history becomes an imperative part of a patent infringement action. The prosecution history before the USPTO of the patent-in-suit is referred to as “intrinsic evidence”, while the foreign prosecution history of a foreign counterpart of the patent-in-suit is referred to as “extrinsic evidence”. Extrinsic evidence includes statements, affidavits, and amendments filed in foreign patent offices.

The US courts may consider both intrinsic and extrinsic evidence to determine the scope and meaning of the disputed claim element. Admissions or statements made during a foreign prosecution can have a significant impact upon the range of equivalents that is available under the doctrine of equivalence.

In general, foreign prosecution might impede a patent holder’s vision for patent protection in the US, or the commercial profiling of the product as envisaged by a company to further its global IP strategy.

Many corporations and law firms in the US have representatives or foreign associates (patent practitioners or IP law firms) in foreign countries who handle the prosecution of an application in the respective patent offices.

In view of the obvious criticality of foreign prosecution records, it is a common practice for foreign associates to seek approval from the in-house counsel or the responsible patent attorney in the US, before responding to objections presented by the foreign patent office.

Patent laws will vary from one jurisdiction to the next, with regard to their applicability and thresholds of patentability. Consequently, approval from the in-house counsel is usually restricted to arguments or responses to non-substantive rejections and may, in exceptional cases, extend to substantive ones.

Nevertheless, it is in the interest of the in-house counsel or the US law firm to maintain uniformity and consistency in patent prosecution as far as possible. A global vision for the doctrine of equivalents analysis should take into account the fact that foreign countries may implement and construe the doctrine in a manner different from the evolving construction implemented by the US courts.

Often, due to reasons like sheer volume, a simple review of draft responses to rejections or the evolution of claims during prosecution in foreign countries becomes a tedious task for the in-house counsel where approval is concerned.

However, such limitations can never take away the significance of foreign prosecution intelligence that can be derived from a study of the evolution of claims in multiple jurisdictions and the analysis of substantive rejections and corresponding arguments. Such a study not only makes global patent prosecution easier, but also prevents dangerous admission or statements, which might pose a threat to the enforcement of the subject patent in the US.

TS Sharat is a senior patent engineer and leads the Intellectual Property Support Services Unit at Clairvolex Knowledge Processes, a Delhi-based legal outsourcing firm.


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