[A] patentee chooses broad claim language at the peril of losing any claim that cannot be enabled across its full scope of coverage.

On August 14, 2012, in MagSil Corp. v. Seagate Tech., the U.S. Court of Appeals for the Federal Circuit (Rader,* O'Malley, Reyna) affirmed the district court's summary judgment that U.S. Patent No. 5,629,922, which related to read-write sensors for computer hard disk drive storage systems, was invalid for a lack of enablement. The Federal Circuit stated:

"To be enabling, the specification of a patent must teach those skilled in the art how to make and use the full scope of the claimed invention without 'undue experimentation.'" The enablement determination proceeds as of the effective filing date of the patent. Enablement serves the dual function in the patent system of ensuring adequate disclosure of the claimed invention and of preventing claims broader than the disclosed invention. This important doctrine prevents both inadequate disclosure of an invention and overbroad claiming that might otherwise attempt to cover more than was actually invented. Thus, a patentee chooses broad claim language at the peril of losing any claim that cannot be enabled across its full scope of coverage. "The scope of the claims must be less than or equal to the scope of the enablement to ensure that the public knowledge is enriched by the patent specification to a degree at least commensurate with the scope of the claims."

The asserted claims of the '922 patent broadly claim any tri-layer tunnel junction device wherein "applying a small magnitude of electromagnetic energy to the junction ... causes a change in the resistance by at least 10% at room temperature." . . . The district court further found that the asserted claims cover "resistance changes beyond 120% and up to infinity." Thus, the specification at the time of filing must teach one of ordinary skill in the art to fully perform this method across that entire scope.

The specification -- the disclosure available to show the full scope of enablement -- teaches that the inventors' best efforts achieved a maximum change in resistance of only 11.8% at room temperature. As the district court noted, MagSil has "not disclaimed the asserted claims' infinite scope in the area of resistive change." Accordingly, this record and specification show that the district court correctly discerned that the asserted claims are not enabled. . . . The '922 patent 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 in 1995, and 604% junctions were not achieved until 2008.

In sum, 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 ordinarily skilled artisan could have achieved the modern dimensions of this art. Thus, 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%.

The open claim language chosen by the inventors does not grant them any forgiveness on the scope of required enablement. Open claim language, such as the word "comprising" as a transition from the preamble to the body of a claim, "signals that the entire claim is presumptively open-ended." "The transition 'comprising' creates a presumption that the recited elements are only a part of the device, that the claim does not exclude additional, unrecited elements." MagSil seeks some easing of the enablement requirement by using this language in the asserted claims.

The '922 patent specification only enables an ordinarily skilled artisan to achieve a small subset of the claimed range. The record contains no showing that the knowledge of that artisan would permit, at the time of filing, achievement of the modern values above 600% without undue experimentation, indeed without the nearly twelve years of experimentation necessary to actually reach those values. The enablement doctrine's prevention of over broad claims ensures that the patent system preserves necessary incentives for follow-on or improvement inventions. In this case, for instance, many additional inventions and advances were necessary to take this technology from a 20% resistance change to the over 600% change in present data storage systems. Moreover this technology area will continue to profit from inventive contributions. Enablement operates to ensure fulsome protection and thus "enable" these upcoming advances.

MagSil's difficulty in enabling the asserted claims is a problem of its own making. This court holds that the asserted claims are invalid for lack of enablement because their broad scope is not reasonably supported by the scope of enablement in the specification. MagSil did not fully enable its broad claim scope. Therefore, it cannot claim an exclusive right to exclude later tri-layer tunnel junctions that greatly exceed a 10% resistive change.