United states patent dating
Another approach to invalidating a patent is to prove that the invention was in public use or on sale in the U. 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. or patented or described in a publication in any country before the invention thereof by the applicant, the patent is invalid.If the technology falls within the claims, the next phase of evaluation is to determine whether the patent is valid. 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.If the patent is invalid, there can be no infringement, regardless of whether the technology is embraced by the claims. 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. Silverman 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.
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.