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TechRoadmap Directions
  IP Issues of Interest to High Tech Companies
Vol 2 Issue 11 December 2002

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Holiday Gift in Lieu of Cards

A Substantial Question

Tip of the Month

IP Links of Interest

On-Line Patent Glossary


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Directions is a newsletter from TechRoadmap Inc. discussing intellectual property issues and ideas. We hope to stimulate you to examine and improve your own IP practices.

Words in a patent sometimes take on a life of their own. On the one hand, a patent is supposed to be a complete and exact description of your invention. On the other hand, no one expects each patent to start at ground zero and teach the entire body of knowledge in the subject at hand. One word which has become standard in patent specifications is "substantially", used to indicate that some property of the invention only needs to be approximately the stated value. To learn why your patent attorney will push you to be more specific, read "A Substantial Question"
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  • A Substantial Question
  There's a joke about the differences between mathematicians, physicists, and engineers, the punch line hinging on the precision with which calculations are made and the difference between theory and practice. In preparing a patent application we are all engineers, required to teach someone skilled in the art how to practice our invention. From the engineer's perspective we know that there are no absolutes; a "substantially flat" surface in optics might only allow for 20 Angstrom bumps but a "substantially flat" asphalt runway will have bumps a million times higher. A recent Appeals Court ruling affirmed that a "substantially" flat surface is properly in the eye of the (skilled in the art) beholder. To learn more, read on...

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  • Tip of the Month
Always review your patent application for relative, as opposed to absolute, descriptive terms. Often more than one relative term can be used to make one's mean more clear:
  • Substantially - A descriptive term used to avoid a strict numerical boundary to the specified parameter. If used alone, leaves a large arguing point, since what is true for one expert may be false to another.
  • Typically - Indicative of what is considered good practice in the art in question. Less arguable if indeed multiple examples can be found in practice.
  • Preferably - Indicates what the inventor believes to be the best, although not the only, value for the parameter.
These terms can be used together, as in: "The window is a substantially flat piece of glass, typically with deviations of less than 1 micron peak-to-valley and preferably with deviations of less than 0.5 microns peak-to-valley."
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  • IP Links of Interest
  US Patent office - Searchable database of all US Patents and, now, published patent applications.
The Patent Cafe - an on-line source of interesting insights into current IP issues.
EKMS Inc. - a company with whom we've worked that provides a range of IP management services including portfolio analysis, deal-making, and process improvement.

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  • On-Line Patent Glossary
  The following link should take you to this same article in the web based version of Directions, where you will find the on-line Patent Glossary.

Industry's Best Glossary
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  • A Substantial Question - continued

Recently, Verve, LLC successfully appealed a ruling that claims in their patent (US 4,850,315) were invalid due to indefiniteness. Their invention - a new push rod - was described in the claims as a "tube having substantially constant wall thickness throughout the length of the tube and the tips thereon." The District Court, in ruling this claim invalid, said "the ambiguity of [the term "substantially"] was [Verve's] willingness to include great variations in wall thickness..." The court ruled that the claim was indefinite because the meaning of substantially constant had not been defined elsewhere in the patent.

The Appeals Court overturned this ruling, pointing out that the law did not require that the specification and prosecution history be the only source of meaning of words used in the patent. Patent documents, they said, are written for persons familiar with the relevant field and the patentee is not required to include in the specification information readily understood by practitioners. (Otherwise, every patent would be a comprehensive tutorial, instead of a concise statement for persons in the field.)

The question is not whether the word "substantially" has a fixed, unambiguous meaning, but rather how will it be understood by a person experienced in the field, upon reading the patent. Relative expressions like substantially are necessary in patent documents to accommodate the minor variations that are appropriate to the invention at hand. In 1988 the court explained that such terms may serve to describe the invention with precision appropriate to the technology.

When you use terms like substantially, closely approximate, or generally you must not use them as a covert way to avoid "particularly pointing out and distinctly claiming" your invention. You can (and should) use them when they reasonably describe the subject matter so that its scope will be understood by persons in the field of the invention. Your patent attorney can suggest the proper balance between precise definitions and reasonably describing the scope of your invention.

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Nothing in the preceding article should be construed as legal advice. TechRoadmap Inc. serves as an interface between companies and their legal counsel.