Patent Validity and Invalidity Opinions

When a company is accused of patent infringement or is seeking to acquire rights to a patent, the first question should be: Is the patent valid and enforceable? In patent infringement actions, invalidity or unenforceability is always the first line of defense. By successfully placing the validity of an issued patent in doubt, the value of the patent declines significantly. This strategy is quite helpful in licensing or acquisition situations.

The first step in determining the validity of a patent is to check whether the patent term has expired or the maintenance fees have not been paid. Next, the patent’s file wrapper or prosecution history should be obtained from the patent office. The file wrapper is a complete copy of the prosecution history of the patent, including all the correspondences between the applicant and the examiner at the patent office from the filing of the original patent application to the issuance of the patent, as well as any corrections submitted after the patent issued. The file wrapper is used to perform claim construction and determine the scope of the claims by taking into account limitations within the file wrapper.

In an effort to find additional prior art that may not have been known to the Examiner or the Applicant at the time of the filing and prosecution, a patent search may be ordered. This is a search not unlike a patentability screening search for a new invention, except that it is based on the issued claims of the patent of interest rather than on a description of the invention. A patentability screening search and opinion is typically requested by the inventor, prior to filing an application; a patent validity search and opinion is normally requested by a third party, after a patent has issued.

When the search is complete, the search results should be compared with the issued claims to determine if and to what extent the claims read on or were anticipated or made obvious by the prior art publications. In the case of an infringement challenge, a formal opinion as to the validity is usually combined with an analysis of the other possible defenses to infringement. A patent validity and infringement opinion favorable to an accused infringer’s position, is an important legal device that may protect against an excessive damages award in the event there is a later judicial finding of infringement.

Patent law and the implications of a patent validity opinions are complex legal matters for which professional counseling is essential.

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