September 2012

Broad Claim Language Must Be Enabled Across Its Full Scope of Coverage
Clara N. Jimenez

In MagSil Corp. v. Hitachi Global Storage Technologies, Inc., No. 11-1221 (Fed. Cir. Aug. 14, 2012), the Federal Circuit affirmed the district court’s grant of SJ of invalidity for lack of enablement of U.S. Patent No. 5,629,922 (“the ’922 patent”), assigned to the Massachusetts Institute of Technology and exclusively licensed to MagSil Corporation (“MagSil”). 

The ’922 patent relates to read-write sensors for computer hard disk drive storage systems.  The sensors use a quantum mechanical effect where the electric current can tunnel from one electrode through a thin insulating barrier layer into a second electrode.  With two ferromagnetic electrodes, the tri-layer tunnel resistance changes with a change in magnetization direction.  The ’922 patent claims a method of manufacturing a tri-layer tunnel junction and the junction itself.  The asserted claims, however, only claim the tunnel junction device. 

MagSil filed suit against several defendants, including Hitachi Global Storage Technologies, Inc., Hitachi America, Ltd., Hitachi Data Systems Corporation, and Shenzhen Excelstor Technology, Ltd. (collectively “Hitachi”), alleging that their disk drive products infringed claims of the ’922 patent.  The non-Hitachi defendants were dismissed from the case.  After claim construction proceedings, the parties filed cross-motions for SJ.  The district court granted Hitachi’s SJ motions of invalidity and noninfringement after finding that the limitation “a change in the resistance by at least 10% at room temperature” was not enabled by the specification.  Because the asserted claims were deemed invalid, the district court also granted Hitachi’s SJ motion of noninfringement. 

On appeal, the Federal Circuit affirmed the district court’s holdings.  The Court reiterated that enablement serves a dual function in the patent system by ensuring adequate disclosure of the claimed invention and preventing overbroad claiming that might otherwise attempt to cover more than was actually invented.  MagSil advocated for a broad construction of the claim terms, relying on, among other things, expert testimony that the claims cover tunnel junctions with resistive changes of 100% or more, with one of the inventors testifying that a 1000% change falls within the scope of the claims.  As construed, the district court found that the asserted claims cover “resistance changes beyond 120% and up to infinity.”  Slip op. at 7 (quoting MagSil Corp. v. Seagate Tech., 764 F. Supp. 2d 647, 680 (D. Del. 2011)).  Thus, the inquiry is whether the specification, at the time of filing, teaches one of ordinary skill in the art to achieve the resistance change across that entire scope.

In analyzing the disclosure at the time of filing, the Court noted that the specification indicated that past efforts had failed to produce an adequate level of changes in the tunneling resistance for practical applications, peaking at only 2.7% change in resistance.  In contrast, the specification explained that the invention of the ’922 patent achieves a “ten percent change in the tunneling resistance with respect to magnetic field (H) variation.”  While the specification discloses a 1975 publication that predicted an ideal tunnel junction could yield around a 24% change in resistance, the inventors’ best efforts, twenty years later at the time of filing, achieved a maximum change in resistance of 11.8% at room temperature.  During prosecution, the inventors asserted that changes of 18% had been achieved after the date of filing, and predicted still higher resistive changes because “no clear theoretical limit prevented achieving the highest possible value of 100%.”  Id. at 9.  The Court found that the inventors’ understanding during prosecution that a 100% resistive change was an upper limit was inconsistent with MagSil’s position at litigation that the claims would cover resistive changes greater than 120%.

In addition, the Court highlighted inconsistencies in the testimony offered by MagSil’s experts indicating that a person of ordinary skill in the art could work the ’922 patent and make tunneling junctions with a resistive change between 100% and 120% without undue experimentation, while also testifying that the first junction with this level of resistive change was not developed until twelve years after the patent application was filed.  The expert had also acknowledged that even someone of extraordinary skill in the art in 1995 could not have predicted the exact process and materials needed for the 120% resistive change achieved over ten years later.  In addition, the expert admitted that resistive change of 604% has now been achieved by others, and the claim scope extends well beyond that value as well.  The Court noted that even if the expert’s testimony could somehow overcome the requirement that the enabling disclosure must appear in the specification at the time of filing, his testimony failed to reach the modern dimensions of the field.

In sum, the Court found that this field of art has advanced vastly after the filing of the claimed invention.  The specification containing these broad claims, however, does not contain sufficient disclosure to present even a remote possibility that an ordinary skilled artisan could have achieved the modern dimensions of this art.  The specification does not disclose working examples of tunnel junctions with resistive changes of 20%, 120%, 604%, or 1000%.  The named inventors were not able to achieve even a 20% change a year after filing the application.  And 604% junctions were not achieved until more than a decade later.  The Court concluded that “the specification enabled a marginal advance over the prior art, but did not enable at the time of filing a tunnel junction of resistive changes reaching even up to 20%, let alone the more recent achievements above 600%.”  Id. at 10.  The Court emphasized that the enablement doctrine ensures that the patent system preserves necessary incentives for follow-on or improvement inventions.  In this case, many additional advances were necessary to take the technology from a 20% resistance change to the over 600% resistance change in present data storage.  Thus, the Court reasoned, this technology area will continue to profit from inventive contributions.  “Enablement operates to ensure fulsome protection and thus ‘enable’ these upcoming advances.”  Id. at 13.

The Court also rejected MagSil’s argument that the open claim language “at least” is equivalent to the Court’s construction of “comprising” in Gillette Co. v. Energizer Holdings, Inc., 405 F.3d 1367, 1371 (Fed. Cir. 2005).  In Gillette, the patentee claimed “[a] safety razor blade unit comprising . . . a group of first, second, and third blades.”  Slip op. at 12 (alterations in original) (quoting Gillette, 405 F.3d at 1369).  The Court found that the claim covered a razor with four blades, because it used the open claim term “comprising” to encompass subject matter beyond a razor with only three blades, and the claim language, specification, and prosecution history supported such breadth.  Id. (citing Gillette, 405 F.3d at 1371-72).  Distinguishing Gillette from the present case, the Court noted that enablement was not an issue in Gillette.  Moreover, the safety razor technology and the very fact-specific distinctions in that case did not apply to MagSil’s technology or case.  Finally, the Court explained that in Gillette, the invention did not claim an infinite number of blades but blades with three separate categories of characteristics.  Therefore, the Court concluded, a limitation extending to an open-ended range of values that must be present for infringement is different from a preamble recitation “comprising,” which does not exclude additional features to devices otherwise within the narrower claim definition.  Accordingly, the Court affirmed the district court’s finding on invalidity and noninfringement.