Patent Drafting Taboos: I. Words that Limit

Certain words in a patent specification may be invitations to limits on the claims.

There are certain words sometimes found in patents that strike fear in the stoney hearts of trial patent attorneys.  These are words that may be used by a Judge in a Markman hearing to more narrowly construe the meaning and breadth of the claims then would be otherwise merited  in their absence.

For those not familiar with the Markman hearing, a District Judge or CAFC Panel has vast and ultimate power in reconstructing the meaning of claim language, and can (not 'may', but 'can' as in "will") look to the specification (or the file jacket)  to interpret the scope of the claims.  This has become a grey area in that limitations from the specification should not be read into the claims, but it is also well established that certain words invite this.  These words in the specification call attention to a particular aspect or embodiment of the invention, and by doing so, invite the judge to limit the scope of the invention to that highlighted embodiment, excluding all others.

As a case in point, consider a patent that claims a composition “comprising a polymer” among other elements.  If a statement in the specification is made to the effect that, “Compositions containing poloxamer were found to be [advantageous, critical, essential, or preferable] in the invention,” then it is within the power of an unsympathetic court to rule that the claim is properly construed to read only on compositions containing poloxamers, particularly if other evidence suggests that the inventor particularly touted these compositions or failed to work with any others.  IF the claim is then read with that limitation in mind, then by summary judgement, an alleged infringer would be free to sell an otherwise  infringing article containing Tweens or Cremophore EL  instead of Poloxamer.  In order to overcome the potential problem, a more encompassing  written description would be, “In one embodiment, the compositions contain polymers of the genus ‘Poloxamer^®’, where Poloxamer is defined as a polymer having…  .”  The term "embodiment" is a broadening term, indicating that only one of a plurality of embodiments being claimed contains Poloxamer.

A prudent patent drafter or wordsmith will develop a list of these words and search each draft application before filing, carefully considering each in context for the weight and possible implication that words of this type may carry.  Recognizing the dramatic damage that a limitation conveyed by a word can do at trial, these words or phrases should be examined carefully before use.  Someone at Finnegan, Henderson Farabow Garrett & Dunner, probably Tom Irving, calls them “patent profanity.”  No matter what you call them, the language is easily corrected in a draft, but impossible to erase from a filed application.  Patent drafters must consider the use of these words as they would be used in an adversarial proceeding.

This list of limiting terms comprises, but is not limited to [to be supplemented as time permits]:

          “The invention …”

          is

         are

          essential

          all

          every

          critical

          necessary

          advantageous

          significant

          majority

          peculiar

          most

          must

          needed

         desirable

          usual

          correct

          requirement

          specify

          expected

          never

          must

          should

          surely

          none

          only

          rarely

          limited success with

          typically

          highly

          absolutely

          frequently

         commonly

         generally

         uncommon

         usually

          few

          partly

          as much as

          special

          conveniently

          difficult

          time consuming

          laborious

Keep in mind that the disclosure must fully, clearly, concisely, and exactly describe the invention.  When you think about it, "fully", "clearly", "concisely" and "exactly" are words that limit.  The court wants to see a "bright line" around the inventive entities, and literal directions or teachings pointing to the specific entities claimed.  

On the other hand, the client is entitled to the full fruits of his invention, and should not see this property right eroded by poor choice of words in the application.  To balance these dual and somewhat conflicting necessities, the patent drafter must choose words with the precision and clarity of language required to meet the statutory requirements of USC 35 §112 ¶1 and yet with sufficient breadth to cover reasonably inclusive embodiments beyond the literal scope of the one, two or ten examples provided in the specification.  The court must not be invited to exercise its considerable power to limit a claim, and hence free an alleged infringer, simply because one of the taboo words of the list above opens an avenue of potential ambiguity that can be resolved against the patentee and result in quick summary judgement in favor of the defendant.  When used, these words should be used only with deliberate intention.

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