This educational guide is based on the linked primary sources. It is not a Court publication, is not affiliated with the Court, and is not legal advice.
In brief
Overview
The case was presented for oral argument before the Supreme Court of the United States.
The case was later submitted to the Court.
Background and question before the Court
According to Festo Corporation (Petitioner), petitioner argues that the Federal Circuit's rules should be reversed because they contradict the Supreme Court’s decision in Warner‑Jenkinson and undermine the patent system.
According to United States (Amicus Curiae), the United States, as amicus curiae, supports vacatur and remand of the case.
According to United States, amicus counsel Lawrence G. Wallace explains that amendments made to avoid prior art are typically narrowing, whereas other amendments are not, and contends that the Federal Circuit’s discussion of “narrowing amendments” mischaracterizes the petitioner’s position.
Respondent, through Mr. Neustadt, argues that the Federal Circuit’s “flexible bar” rule improperly permits a doctrine‑of‑equivalents claim by allowing a party to equate “glue” with “adhesives,” and that such practice should not be allowed.
Mr. Neustadt estimates that roughly fifty percent or more of patent applications involve the issues under discussion.
Justice asks whether there is a relevant difference between claim elements and claim limitations.
According to Justice (unspecified), justice asks whether transferring the dispute to the Patent Office’s appeals process will result in a long, protracted timeline.
- [1] 649bd1c2c85ed43ead0a-r1-764460c4beaa03fd.pdf, p. 3
- [2] 649bd1c2c85ed43ead0a-r1-764460c4beaa03fd.pdf, p. 1
- [3] 649bd1c2c85ed43ead0a-r1-764460c4beaa03fd.pdf, p. 21
- [4] 649bd1c2c85ed43ead0a-r1-764460c4beaa03fd.pdf, p. 34
- [5] 649bd1c2c85ed43ead0a-r1-764460c4beaa03fd.pdf, p. 36
- [6] 649bd1c2c85ed43ead0a-r1-764460c4beaa03fd.pdf, p. 20
- [7] 649bd1c2c85ed43ead0a-r1-764460c4beaa03fd.pdf, p. 36
What each side argues
FESTO CORPORATION (Petitioner)
According to Festo Corporation (Petitioner), petitioner argues that the Federal Circuit’s rules should be reversed because they conflict with the Supreme Court’s Warner‑Jenkinson decision and damage the patent system.
Respondent (represented by Mr. Neustadt)
According to Mr. Neustadt, respondent contends that the Federal Circuit’s “flexible bar” rule improperly allows a doctrine‑of‑equivalents claim by equating “glue” with “adhesives,” and that such practice should be prohibited.
What happened at oral argument
Oral argument began at 10:16 a.m.
What the Court decided
Why it matters
Terms to know
No glossary terms are available for this guide.
Primary sources
Read the source materials on the official site or open the immutable repository copy used for this guide.
- 649bd1c2c85ed43ead0a-r1-764460c4beaa03fd.pdforal argument transcript
Guide generated September 19, 2026. Automated validation accepted this version.