Perhaps the best example is given in Brenner v. United States, 773 F.2d 306 (Fed. Cir. 1985). The patented invention concerned a system for coding and sorting mail. The claims described a means for applying a "codable" material, such as a magnetic strip, to an article of mail. The material would carry the information needed for the sorting. When the patent application was initially filed, the claims referred to a "coded" rather than "codable" material, implying that the information was encoded beforehand. However, during prosecution the applicant changed the claim language to "codable," telling the examiner that the new language more accurately described the invention "since when the material is placed on the mail it is not yet coded." When compelled to distinguish certain prior art, the applicant stressed this distinction and also emphasized that the material could be erased after encoding.
The system accused of infringing used an ink jet printer to spray bar codes directly on the mail to be sorted. The only article applied to the mail was the ink itself, and the ink was not codable. By the time the ink hit the paper, it was fixed in a predetermined pattern, and it could not be altered or erased afterward. The trial court, affirmed by the Federal Circuit, found that the accused system could not be held equivalent to the system claimed because the applicant during prosecution had clearly limited the invention to "codable material." Id. at 308.
The system accused of infringing used an ink jet printer to spray bar codes directly on the mail to be sorted. The only article applied to the mail was the ink itself, and the ink was not codable. By the time the ink hit the paper, it was fixed in a predetermined pattern, and it could not be altered or erased afterward. The trial court, affirmed by the Federal Circuit, found that the accused system could not be held equivalent to the system claimed because the applicant during prosecution had clearly limited the invention to "codable material." Id. at 308.