An often-overlooked aspect of patent drafting is the requirement under 35 U.S.C. § 112, ¶ 1 that the entire scope of the claims must be enabled by the disclosures in the specification. As can be seen from the Federal Circuit’s recent decision in Magsil Corp. v. Hitachi Global Storage Technologies, Inc., Case No. 2011-1221, the failure to fully enable a claim can have grave consequences.
The case involved read-write sensors for computer hard disk drive storage systems. The inventors claimed a method of manufacturing a tri-layer junction and the junction itself. Information is stored by varying the magnetization of an electrode on the hard disk. In one orientation, the resistance is higher than the other, which can be measured to determine whether the electrode is in a “0” or “1” state. At issue was the phrase “causes a change in the resistance by at least 10% at room temperature.” Past inventions were unable to achieve this large of a change, peaking at only 2.7%.
The problem for the patentee was the open-ended language of “at least 10%,” which the Court noted could include changes from 10% to infinity. The specification only described how to achieve changes between 10.0–11.8%, and was silent on how to achieve changes larger than that. The district court granted summary judgment for the defendant, finding that the claims were not enabled and therefore invalid, and the Federal Circuit affirmed.
The Federal Circuit reviewed the history of the full scope enablement requirement, which serves two purposes—(1) to ensure that the patentee adequately discloses the claimed invention and (2) to prevent claims that are broader than what is disclosed. The Court noted that “a patentee chooses broad claim language at the peril of losing any claim that cannot be enabled across its full scope of coverage.” Therefore, in order to meet the enablement requirement, “[t]he specification must contain sufficient disclosure to enable an ordinary skilled artisan to make and use the entire scope of the claimed invention at the time of filing” without undue experimentation.
In this case, the Court found that the claim was invalid because the specification did not enable the full scope of the claims. There was nothing in the specification that described how to achieve changes of the magnitude encompassed by the open-ended claim. In fact, the inventor testified that even he did not know how to create changes greater than 20%. Because “[t]he ‘922 patent specification only enables an ordinarily skilled artisan to achieve a small subset of the claimed range,” the Federal Circuit affirmed the district court’s summary judgment of invalidity.
This case provides an important practice pointer when drafting claims. While one is generally interested in drafting broad claims, it is important that the specification fully supports the range of the claims; otherwise, the entire claim might be invalid. This further suggests that drafters consider using dependent claims to narrow ranges or using so-called “picture” claims, which are more tightly focused on any embodiments known to the inventors at the time of the application.