On January 14, 2025, the United States Court of Appeals for the Federal Circuit issued a pivotal decision in Lynk Labs, Inc. v. Samsung Electronics Co., Ltd., affirming the invalidation of certain claims in Lynk Labs’ U.S. Patent No. 10,687,400 (the ’400 patent) through inter partes review (IPR). The case primarily addressed a critical question in patent law: when does a published patent application qualify as prior art in an IPR? The Federal Circuit confirmed that a published patent application can be deemed prior art as of its filing date, significantly impacting how prior art is evaluated in IPR proceedings.

Background of the Case

The ’400 patent, held by Lynk Labs, pertains to alternating current (AC) driven LED technology. Samsung challenged the validity of claims 7–13 and 15–17 of the patent under 35 U.S.C. § 103 (obviousness), relying in part on U.S. Patent Application Publication No. 2004/0206970 (referred to as “Martin”). While the Martin application was filed before the priority date of the ’400 patent (February 25, 2004), it was not published until October 21, 2004. Lynk Labs contended that because Martin was not publicly available before the priority date, it should not be considered prior art in the IPR proceeding.

Key Legal Issue: Prior Art Status of Published Patent Applications

Lynk Labs argued that under the traditional understanding of prior art printed publications under 35 U.S.C. § 102(a) and (b), a reference must be publicly accessible before the relevant priority date to be considered prior art. In contrast, Samsung maintained that under § 102(e)(1), a U.S.-filed patent application published under 35 U.S.C. § 122(b) can be treated as prior art as of its filing date, regardless of when it became publicly accessible.

The Federal Circuit sided with Samsung, holding that under § 102(e)(1), a published patent application serves as prior art as of its filing date, provided it was filed before the claimed invention. This interpretation aligns with prior cases recognizing that patents granted on such applications are also considered prior art as of their filing date under § 102(e)(2). The ruling underscores that Congress intended a different treatment for published patent applications compared to other printed publications such as journal articles and technical papers.

Implications for Intellectual Property Law

The Federal Circuit’s decision has significant implications for patent owners and IPR petitioners:

1. Expanded Scope of Prior Art in IPRs: This ruling solidifies that a published patent application can be used as prior art in an IPR based on its filing date, even if it was not publicly available before the challenged patent’s priority date. This expands the range of prior art that can be leveraged in patent challenges.
2. Greater Risk for Patent Holders: Patent applicants must be aware that even unpublished applications filed before their invention can be cited against them in an IPR, potentially increasing the risk of invalidation.
3. Strategic Considerations for Patent Drafting: Innovators should carefully evaluate their filing strategies, including provisional applications and continuation practices, to ensure that their own filings are structured to avoid unintended prior art issues.

Other Legal Issues Addressed

Beyond the prior art issue, the court also reviewed claim construction disputes:

• Series Connection of LEDs: The court upheld the Board’s broad interpretation of “a plurality of LEDs connected in series” to include both individual LEDs and LED circuits. This reinforced the principle that claim terms should be interpreted based on intrinsic evidence from the specification.
• Matching Forward Voltage to Rectified Input AC Voltage: The court also agreed with the Board’s interpretation that “matches” does not require an exact equivalence but can include cases where the input voltage is less than or equal to the LED circuit’s forward voltage.

Conclusion

The Federal Circuit’s ruling in Lynk Labs v. Samsung provides crucial clarity on how published patent applications function as prior art in IPRs. By affirming that such applications can serve as prior art as of their filing date, the decision strengthens the ability of IPR petitioners to challenge patents using prior-filed but later-published applications. For patent holders, this ruling serves as a reminder to carefully consider prior filings when assessing patentability and preparing for potential IPR challenges. As the landscape of patent litigation continues to evolve, this case stands as a key precedent in the interpretation of prior art rules under U.S. patent law.

By Charles Gideon Korrell