Facts of case
In the following case, the patent claim at issue is directed to computer hard disk drive storage systems. Magsil v. Hitachi (Fed. Cir. 2012). Without boring everyone with the technical specifics, the patent claim defined the claimed invention by describing the end result, namely, a change in resistance in a disk storage device by at least 10% at room temperature. In the patent specification, the inventor disclosed a maximum change of resistance slightly above 10% (i.e., 11.8%). In the prior art, only a change of resistance up to 10% at room temperature was achievable.
Progress of technology
Hard disk manufacturing improved over the course of the next 10 years after the patent was filed. Hard disk manufacturers are now able to achieve a change of resistance of 600%. This is a significant change over the prior art as well as the improvements patented by the inventor of the patent at issue and its improvement of 11.8%.
Claiming too much is problematic
U.S. patent laws require the inventor to describe the invention and enable the full scope of the claimed invention so that after the patent expires, those of ordinary skill in the art can practice the patented technology, and so that those skilled in the art can improve upon the disclosed invention during the patent’s life – but in non-infringing ways. Here, the defendant argued that the inventor did not enable the full scope of the claimed invention in that the inventor did not describe a way of achieving large changes of resistance over and above what the inventor was able to achieve, namely, 11.8%. As such, the Court granted summary judgment (i.e., without going through trial) which invalidated the claim at issue for lack of enablement. In other words, the Court found that the patent’s specification did not enable one to achieve resistance changes from 10% to infinity, which is what the claim literally covered since the claim language of at least 10% does not have an upper limit. Hence, the patent claim was held to be invalid for lack of an enabling disclosure.
Specifying a minimum number
One interesting issue that the patentee tried to argue was that they compared the claim at issue with Gillette’s patent claims directed to the Mach 3 razor blade. In Gillette’s patent, the claims recite first, second and third blades. As a result, the claims of the Gillette patent recites a lower limit of 3 blades but no upper limit since the claims could literally encompass a razor with 3,000 blades which would not have been enabled by the specification. The Court responded that the Gillette patent litigation never raised lack of enablement and that the recitation of first, second and third blades in the Gillette patent does not specify a number of blades but blades with three separate categories of characteristics.
Claim and patent specification strategy
When drafting patent applications, this case illustrates the importance of bounding upper and lower limits of ranges, not only in the specification but also in the claims. Moreover, one might consider patenting the key feature that enables the higher range. For example, if the higher range is achievable through use of a particular material, process or arrangement, then it could be beneficial to add one independent claim directed to the key feature that enables the higher range without specifying the upper limit and a second independent claim directed merely to the elevated range.
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