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Clearance Search Review

March 24, 2010

As a follow-up from a previous post on types of patent searches [Link], this post discusses some techniques for reviewing patent documents (both patents and patent applications) for potential relevance for a given product, and the post provides some choices for action taken in case a patent document is deemed relevant based on the review.

A preliminary review of a given patent document helps to form an initial interpretation of what the scope of the claims is.  Intrinsic evidence is used to determine the claim meaning, with this type of evidence including e.g., the specification and listed embodiments, the document’s prosecution history, cited prior art, other claims within the patent document, associated patent litigation, and associated parent/sibling/foreign filings.  The ordinary meaning of each claim is construed from the perspective of a person having ordinary skill in the art (PHOSITA) for the time period of the invention.  However, an inventor in the patent document specification can expressly define terms differently than their ordinary meaning, and the specification may explicitly disclaim some embodiments.  Of course means-plus-function claims are limited the structures and equivalents contained within the spec.  Also, during patent prosecution the patent owner can surrender claim scope.

Extrinsic evidence such as a dictionary definition or expert testimony, or even inventor testimony, can be used to determine the claim construction if it does not contradict the intrinsic evidence.  The proper construction is weighed heavily toward the intrinsic evidence such as those listed in the paragraph above.

If a patent document under review seems potentially relevant to a given product (planned or existing), then there are various options that could be entertained, each with its own associated trade-offs:

  • Performing a workaround so as to avoid possible infringement, if such a workaround is feasible.  Any workaround considered should be analyzed to ascertain its impact on the product — its impact on cost, quality, and timeliness of the product should not be more detrimental than other possible routes, such as obtaining a license.  Also, it is often advisable to obtain a written opinion from external patent counsel on the non-infringement of the workaround on the patent.
  • Forgoing the product altogether.
  • Licensing the patented invention from the patent owner, whether through monetary payment, cross-licensing of patents, etc.
  • Obtaining an opinion from external patent counsel of prior art anticipation or obviousness of the patent.  This type of opinion is more difficult to obtain, as in this case every claim needs to be shown to be invalid.  Additionally, this type of opinion is certainly not rock solid, as the patentee can render the opinion moot such as through claim modification in a reexamination (e.g., adding an element to claims to avoid invalidity finding by examiner).
  • Obtaining an opinion from external patent counsel of non-infringement.  This type of opinion only has to show non-infringement of the independent claims, as a product that does not infringe independent claims cannot infringe the dependent claims.
  • Taking a chance and doing nothing.  The risks here are obvious, as there could be problems with “willful infringement”.  Consider also that a given patent may not be in force due to a missed maintenance fee, but one needs to be careful here since patents can be revived.

None of these decisions can be taken lightly, and due consideration should be given to each.  The above list is not meant to be exhaustive, as there are further considerations that can made in this situation.  Additional suggestions are welcomed from readers.

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