The following article appears in the journal JOM, 42 (7) (1990), p. 46. JOM is a publication of The Minerals, Metals & Materials Society

Evaluating the Validity of a United States Patent

In considering whether a specific product, apparatus, method or composition of matter may violate a United States patent, primary attention is directed toward the issues of infringement and validity. Infringement in this context means that the particular technology falls within the patent claims. If the technology falls within the claims, the next phase of evaluation is to determine whether the patent is valid. If the patent is invalid, there can be no infringement, regardless of whether the technology is embraced by the claims.

A United States patent is presumed to be valid. Such presumption is, however, rebuttable. As an initial step in evaluating the validity, it is frequently desirable to obtain a copy of the United States' Patent and Trademark Office's "file wrapper." The file wrapper contains a copy of the application as filed and the communications between the applicant and the Patent and Trademark Office which resulted in issuance of the patent. A review of the file wrapper frequently enables one to determine what rejections of claims were made by the patent office examiner, on what grounds those rejections were made, and what prior art was made of record. This generally provides some insight into what the examiner felt was patentable and what concessions or representations were made by the applicant.

Once one has determined the degree of relevance of the prior art cited by the examiner, one may determine what might be sought through searching for prior art which would be more relevant to the issue of patentability and validity.

One of the principal ways of overcoming the presumption of validity is to attempt to find prior art which is more relevant to patentability of the claims than the prior art which was cited by the Patent and Trademark Office examiner. Such prior art may, for example, take the form of prior patents or publications. The effective prior-art date of a U.S. patent (issued more than a year before the filing date of the patent being evaluated) is the date the prior-art patent was issued.

If the prior-art patent was issued within one year prior to the application filing date which eventually became the patent being evaluated, the effective prior-art date of the patent is the filing date of the application which became the prior-art patent. With respect to publications and foreign patents, it is necessary to look at the date of actual publication or opening to the public.

While the minimum acceptable date of prior art is a date preceding the filing date of the patent application which became the patent being challenged, it is preferable to seek prior art with a date more than one year earlier than the filing date of such application. The reason for this is that if the prior-art publication or patent has an effective date more than one year prior to the filing date of the patent in question, the patent owner is precluded from proving invention earlier than the prior art. If, however, the publication and patent-issue date is within one year of the filing date, the patentee has an opportunity to prove that his or her invention was created prior to the effective date of the reference, thereby eliminating the reference.

Another approach to invalidating a patent is to prove that the invention was in public use or on sale in the U.S. more than a year prior to the date of the application.

If one can prove that the invention was known or used by others in the U.S. or patented or described in a publication in any country before the invention thereof by the applicant, the patent is invalid.

In order to obtain a patent, the invention must be useful, novel and unobvious. Useful means that the invention is capable of serving a useful purpose. Novelty in this context means that the invention was not fully disclosed in a single prior-art reference. The obviousness standard refers to the invention not being obvious to one skilled in the art to which the invention pertains on the basis of a single reference or a combination of references. In making decisions on these three issues, consultation with technical experts in the field of technology involved can be helpful.

Where possible, it is frequently desirable to obtain information regarding the actions of the inventors in dealing with the claimed invention. For example, if the inventor has derived the invention from another, the patent is invalid.

The patent statute requires that the specification disclose the invention in such a manner as to enable any person skilled in the art to which it pertains to make and use the same. It further requires that the disclosure reveal the "best mode" contemplated by the inventor of carrying out the invention. Failure to comply with either of these disclosure requirements can result in the patent being invalid.

The statute also requires that the specification conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his or her invention. Failure to do so can result in patent claims being held invalid. The underlying rationale for this requirement is that the patentee must set forth clearly the line of demarcation between what is protected by the patent and what is not in order that a third party may have a reasonable standard by which to determine whether particular conduct will infringe the patent.

For purposes of evaluating validity, each patent claim is considered separately. While it is entirely possible that prior art will invalidate all of the claims, it is frequently true that some claims are invalidated while others remain valid. In such a situation, one must determine whether there are ways of avoiding the coverage of the valid claims. If one concludes that a patent is valid and would be infringed by a particular practice, the obvious alternatives would be to pursue an approach which does not infringe the patent or to consider making inquiry of the patent owner to determine whether a patent license would be available.

While the foregoing does not purport to provide an exhaustive listing of the various ways in which patent validity may be evaluated, it is hoped that it will provide an enhanced understanding of some of the major considerations generally involved in such evaluations.