The following article appears in the journal JOM, 47 (1) (1995), p. 50. JOM is a publication of The Minerals, Metals & Materials Society

The Relationship Between Basic and Improvement Patents

The term "basic patent" is frequently used to refer to a pioneering type of patent, such as a patent for the first laser or other comparable earthshaking technology. For the purpose of this article, however, a basic patent may be considered to be any prior patent. An improvement patent is one which adds to the technology of the basic patent.

In comparing a basic patent and an improvement patent, one may consider whether the improvement technology is patentable over the basic patent. If a third party owns the basic patent, it may also be determined whether the improvement patent can be practiced without infringing the basic patent. In the technical patent context, the word "improvement" generally means technology that builds directly upon a basic patent. In a broader sense, an improvement may be considered to be something that modifies portions of the technology of the basic patent as distinguished from merely providing an alternate approach to achieving the same result.

Different approaches are taken to determine patentability and infringement. In considering the patentability of an improvement over a prior patent, compare the complete disclosure of the prior patent to determine what it would teach one skilled in the art and then compare that teaching with the improved technology. In evaluating infringement, focus on the claims of the prior patent and compare them with the improvements.

When considering patentability of an improvement, the entire disclosure of the basic patent is reviewed in order to ascertain whether there are meaningful technical differences between the disclosure of the basic patent and the improvement. If there are technical differences, the improvement has requisite statutory novelty. The next question is whether the differences between the improvement and the disclosure of the basic patent are such that one skilled in the art to which the improvement relates would find the differences obvious at the time the invention was made. If such differences are obvious, then the improvement is not patentable. For example, consider a basic patent that discloses a metal alloy consisting of a base metal and alloying constituent A, which is present in a specified range of weights. The improvement relates to the addition of alloying constituent B in a specified weight to the basic alloy. The central issue would be whether the addition of B would be obvious over the basic patent and any other relevant prior art. In making this evaluation, not only must the obviousness of the use of B be considered, but also whether the amounts employed and results obtained would be obvious. Were any unexpected beneficial properties obtained? Are there any economic, process, or environmental advantages achieved through the use of constituent B? These differences and others can contribute to patentability.

U.S. patent law enables the inventive entity (i.e., the same inventor or same group of inventors) named in the basic patent to, under certain circumstances, avoid the basic patent being deemed prior art, which is citable against an improvement patent application. If the same inventive entity named in the basic patent files an application on the improvement within one year after issuance of the basic patent, the basic patent is not prior art citable against the improvement application. This is because the statute requires that prior art of this type be invented by another. The identity of the inventive entity in this example means that the basic patent was not issued for the invention of another. If, however, the patent application directed toward the improvement is filed more than one year after the basic patent issues, regardless of inventorship, the basic patent will be a prior art reference that must be considered in evaluating patentability.

Thus far, this article has centered on the evaluation of whether a patent can be obtained for an improvement invention as compared with a basic prior patent. Another issue of importance is whether someone obtaining an improvement patent can practice the improvement without infringing the basic patent.

There is a common misconception that obtaining a patent gives the right to practice the patented invention. A patent grants the patent owner a negative right (i.e., the right to prevent others from making, using, or selling the patented invention); it does not give the patentee the right to practice the invention. In many instances, a patented improvement cannot be made, used, or sold without infringing the basic patent.

A simplistic example: a basic patent is obtained for a chair having three legs. Another may decide that a chair would be more stable if it had four legs and obtains a patent for a chair with four legs. The improvement patent would give the owner the right to keep others from making, using, or selling chairs having four legs. As the original patent claimed a chair with three legs, making, using, or selling the four-legged version would infringe the basic patent. The presence of an additional leg permits the inventor of the improvement to obtain a patent, but does not avoid infringement of the basic patent for a chair with three legs.

The analysis between a basic patent and an improvement patent, therefore, involves an initial inquiry as to whether the issue is one of patentability over the basic patent or infringement of the basic patent. The factual determinations and legal evaluations are different depending upon which type of evaluation is being made.

In evaluating patentability in comparing a basic patent with an improvement patent, not only the technology involved but also the identity of the inventors can be important. If there is common ownership or if a license has been granted by the owner of the basic patent to the owner of the improvement, infringement would not be a problem.