Intellectual Property Rights

Festo Corporation v. Shoketsu Kinzoku Kogyo Kabushiki Co.

535 U.S. 722 (2002)

Facts

Festo owned patents concerning magnetic rodless cylinders used in industrial machinery.
During patent prosecution, Festo amended its claims by adding limitations.
The amendments helped overcome objections raised by the Patent Office.
Shoketsu manufactured an accused device that did not literally satisfy every amended claim limitation.
Festo therefore relied upon the doctrine of equivalents.
Shoketsu argued that Festo had surrendered the relevant territory when it narrowed its claims.
The Federal Circuit adopted a complete-bar rule:
any narrowing amendment made for patentability prevented the patentee from claiming any equivalent for that element.
Festo appealed to the United States Supreme Court.

Whether every narrowing amendment connected with patentability completely bars the doctrine of equivalents.
What territory is presumed surrendered through amendment.
Whether and how a patentee may rebut prosecution-history estoppel.

Prosecution-history estoppel prevents a patentee from later reclaiming subject matter surrendered to obtain the patent.
A narrowing amendment made for a reason related to patentability creates a presumption that the patentee surrendered the territory between:
the original claim; and
the amended claim.
The presumption is not an absolute bar to every equivalent.
A patentee may rebut it by showing, for example, that:
the alleged equivalent was unforeseeable at the time of amendment;
the reason for the amendment was only tangentially related to the equivalent;
some other reason prevented the patentee from reasonably describing the equivalent.
The patentee bears the burden of rebutting the presumption.

Claim amendments communicate important information to competitors.
When an applicant narrows a claim to obtain a patent, the public may reasonably understand that some subject matter has been given up.
Allowing the patentee freely to reclaim all that territory through equivalence would undermine public notice.
The Federal Circuit, however, had gone too far by imposing a total bar.
Patent applicants cannot always foresee every technological substitute that may later perform an equivalent role.
A complete bar would make the doctrine of equivalents practically disappear whenever a claim had been amended.
That result would encourage imitators to avoid infringement through minor later-developed substitutions.
The Court therefore adopted a middle position.
A patentability-related amendment presumptively surrenders equivalents, but the surrender is measured according to what the amendment reasonably communicates.
If a substitute was unforeseeable when the claim was amended, the applicant could not fairly have been expected to claim it.
If the amendment addressed a different problem, it might bear only a tangential relationship to the accused equivalent.
In such situations, estoppel should not automatically apply.
Festo had to establish that the particular accused equivalent fell within one of the recognised grounds for rebuttal.
The Supreme Court did not itself finally determine whether Festo had rebutted the presumption on the complete factual record.

The Supreme Court rejected the Federal Circuit’s complete-bar rule.
A narrowing patentability amendment creates a rebuttable presumption of surrender.
The patentee may still invoke equivalence by proving unforeseeability, tangential relation or another adequate justification.
The case was remanded for application of that standard.
Use this case for: a narrowing amendment presumptively limits equivalents, but does not automatically eliminate all protection under the doctrine of equivalents.