In Plantronics, Inc. v. Alph, Inc., the Federal Circuit rejected arguments that the election made in response to the Restriction Requirement limited the scope of the claims in a manner that was not reflected in the claim language, specification, or prosecution history. Although the patent holder prevailed on this issue, this case serves as a reminder that every stage of prosecution can give rise to prosecution history estoppel.

The Patent At Issue

The patent at issue was Plantronics’ U.S. Patent 5,712,453, directed to a “Concha Headset Stabilizer.” As explained by the Federal Circuit, the invention relates to “headsets used for cell phone receivers.” Claim 1 recites:

1. An apparatus for stabilizing a headset including a receiver sized to fit between a tragus and an anti-tragus of an ear, the apparatus comprising:
an ear cushion dimensioned to cover a portion of the receiver disposed between the tragus and the anti-tragus;
a resilient and flexible stabilizer support member coupled to the ear cushion, and dimensioned to fit within an upper concha with the ear cushion coupled to the receiver and the receiver disposed between the tragus and the anti-tragus; and
a concha stabilizer pad coupled to the stabilizer support member, for contacting the upper concha.

The Claim Construction At Issue

As summarized by the Federal Circuit, “[t]he district court construed ‘stabilizer support member’ as ‘an elongated structure that extends from the ear cushion to the concha stabilizer pad and stabilizes the headset’ and construed ‘concha stabilizer’ as ‘an elongated stabilizing structure, which extends between the ear cushion and the upper concha.”

According to the Federal Circuit, the “elongated” limitation was not supported by the claim language:

[W]hile the claims are instructive as to the general dimensions of a “stabilizer support” and a “concha stabilizer,” they do not require any particular structure, e.g., one that is longer than it is wide.

or even the specification, which disclosed several embodiment of the “stabilizer support,” only one of which was “elongated.”

The Restriction Requirement 

Aliph’s claim construction arguments focused on the Restriction Requirement.

The Examiner issued a Restriction Requirement based on the finding that the figures revealed four patentably distinct inventions that were recited in the claims: (1) Figures 1A/1B; (2) Figure 2A; (3) Figure 2B; and (4) Figure 2C. Plantronics elected the invention of Figures 1A/1B, and asserted that claim 11 was generic.

Aliph argued that the “claims must be limited to the disclosures and embodiments pertaining to Figures 1A and 1B,” which do not depict arch-shaped or torus-shaped stabilizer supports, but rather appear to depict elongated supports.

No Clear And Unmistakable Disavowal

The Federal Circuit rejected Aliph’s arguments, because the record did not reveal a clear and unmistakable disavowal of embodiments where the stabilizer support is not elongated. For example, the court noted:

  • The Examiner did not explain the basis for the Restriction Requirement, and did not identify the apparently “elongated” stabilizer support of Figures 1A/1B as a distinguishing feature.
  • The other figures depicted devices with “elongated” stabilizer supports.
  • Neither the Examiner nor Plantronics discussed distinguishing features of the elected invention.
  • Plantronics asserted that claim 11 was generic.

The court also noted that, as a general rule:

Patent drawings … do not define the precise proportions of the elements and may not be relied on to show particular sizes if the specification is completely silent on the issue.

Thus, the Federal Circuit reversed the district court’s claim construction, vacated its non-infringement finding, and remanded for further proceedings.

Any Response Can Give Rise To Prosecution History Estoppel

This decision stands in contrast to the Federal Circuit’s May 2013 decision in Uship Intellectual Properties, LLC v. United States, where the court found prosecution history disclaimer based on arguments made against a Restriction Requirement. While the court here did not find estoppel because the prosecution history was silent on the limitation at issue, its scrutiny of the Restriction Requirement and response indicate that almost any response could give rise to prosecution history estoppel.