Background
Aqua Products held U.S. Patent No. 8,273,183, covering a self-propelled robotic pool cleaner. When a competitor challenged the patent via inter partes review (IPR) at the PTAB, Aqua Products sought to amend its claims — a right expressly granted to patent owners by the America Invents Act. Under PTAB regulations and practice, the burden of proving that proposed amended claims were patentable fell on the patent owner, not on the petitioner who was challenging the patent.
In practice, this burden allocation made successful claim amendments extremely rare: patent owners effectively had to prove a negative (that no prior art would render the amended claims obvious) rather than requiring petitioners to identify prior art and prove unpatentability. Aqua Products argued this burden allocation violated 35 U.S.C. § 316(e), which provides that the petitioner “shall have the burden of proving a proposition of unpatentability by a preponderance of the evidence.” The Federal Circuit took the case en banc to resolve the question.
The Court’s Holding
The en banc Federal Circuit vacated the PTAB’s decision and held that the petitioner bears the burden of proving the unpatentability of proposed amended claims — the patent owner does not bear the burden of proving patentability. The plurality opinion, written by Judge O’Malley and joined by six judges, found that 35 U.S.C. § 316(e) unambiguously places the burden of proving unpatentability on the petitioner for all claims — including amended claims proposed by the patent owner. The statute’s plain language does not distinguish between original claims and amended claims; the petitioner must prove unpatentability for all of them.
Although nine judges agreed on the outcome (vacate and remand), they produced five separate opinions and could not agree on a full majority rationale. The court remanded for the PTAB to assess the patentability of Aqua’s proposed amended claims without imposing the burden on the patent owner, and directed the PTAB to apply this new burden allocation in all pending IPR proceedings unless the USPTO engaged in formal notice-and-comment rulemaking to justify a different allocation.
Key Takeaways
- The burden of proving that amended claims are unpatentable in IPR belongs to the petitioner — not to the patent owner proposing the amendment — under 35 U.S.C. § 316(e).
- The decision overturned years of PTAB practice that had made successful claim amendments in IPR extremely difficult, potentially opening a meaningful amendment pathway for patent owners.
- Despite nine judges agreeing on the outcome, five separate opinions produced no single majority rationale — leaving implementation questions for the PTAB and future cases.
- The USPTO subsequently engaged in notice-and-comment rulemaking and in 2019 issued rules codifying the burden-shifting framework, partially restoring some of the PTAB’s prior practice while complying with Aqua Products.
Why It Matters
IPR proceedings had become the dominant vehicle for invalidating patents, with petitioners (typically large technology companies defending against patent suits) winning far more often than patent owners. One reason was the near-impossibility of successful claim amendment: few patent owners could clear the hurdle of proving amended claims were patentable without the adversary being required to identify specific prior art against those amendments.
Aqua Products shifted the dynamics by forcing petitioners to actually challenge amended claims rather than simply sitting back while patent owners struggled to prove a negative. For patent owners — particularly smaller innovators and universities — this was a meaningful improvement in IPR fairness. For technology defendants who relied on IPR as a powerful invalidity tool, the decision added a new strategic wrinkle: proposed amendments could no longer be assumed to fail, and petitioners needed to be prepared to mount an affirmative case against any narrowed claims the patent owner might propose.