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
According to Microsoft Corporation, microsoft argues that the default preponderance of evidence standard should apply to patent invalidity, rather than the clear‑and‑convincing standard.
Justices asked about the burden of persuasion and the presumption of validity in patent cases.
Background and question before the Court
According to Justice Alito, what standard of proof should apply to a claim of patent invalidity?
According to Justice Sotomayor, how does the statutory presumption of validity affect the burden placed on a challenger?
What each side argues
Microsoft Corporation (Petitioner)
According to Microsoft Corporation, microsoft contends that the preponderance of evidence standard, not clear and convincing evidence, should govern patent invalidity determinations.
i4i Limited Partnership (Respondent)
Source-limited. The record does not yet support a complete account.
What happened at oral argument
Justice Alito asked whether the challenger must bear both the burden of persuasion and the burden of production on the issue of invalidity, given the presumption that a patent is valid.
According to Justice Sotomayor, justice Sotomayor questioned why the statute’s presumption of validity requires an additional sentence placing the burden of persuasion on the challenger.
Justice Alito also asked why re‑examination is sufficient to address concerns about patent validity.
According to Justice Breyer, justice Breyer inquired about the heightened standard of proof when the Patent Office has considered the issue or could have reconsidered it.
The court noted that a patent is presumed valid until the presumption is overcome by convincing evidence of error.
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.
- 0ce36499013f1c6c9795-r1-3f974d7d6a34f70f.pdforal argument transcript
Guide generated September 24, 2026. Automated validation accepted this version.