Filing Date Defines Prior Art Status of Published Patent Applications
By Babak Akhlaghi on January 24, 2025. Understanding when a published patent application qualifies as prior art is critical in patent disputes. A recent case, Lynk Labs, Inc. v. Samsung Electronics Co., Ltd., Case No. 23-2346 (Fed. Cir. Jan. 14, 2025) (Prost, Lourie, Stark, JJ.), serves as a critical reminder of a key principle in patent law. Here’s what you need to know.
Lynk Labs appealed a Patent Trial and Appeal Board (PTAB) decision after the Board found certain claims of its U.S. Patent No. 10,687,400 related to LED technology used for lighting signs and decoration such Christmas tree lighting unpatentable during an inter partes review (IPR). At the heart of the case was a key question about prior art timing in IPR proceedings: Can a published patent application be considered prior art as of its filing date or only as of its publication date?
The Federal Circuit’s Answer
The Federal Circuit upheld the PTAB’s decision and provided clarity on this issue. It confirmed that under U.S. patent law—specifically 35 U.S.C. § 102(e)(1)—a published patent application is deemed prior art as of its filing date, even if the publication itself occurred after the priority date of the disputed patent. This interpretation relies on the plain language of § 102(e)(1), which treats a published patent application as prior art if it was filed before the invention date of the challenged patent.
The Case Breakdown
The challenge stemmed from Samsung’s use of a published patent application (Martin) to argue that claims in the ’400 patent were unpatentable for obviousness. Martin was filed before the ’400 patent’s priority date but published months later. Lynk Labs contended that Martin should not qualify as prior art because it was not publicly accessible until after the ’400 patent’s priority date.
The Federal Circuit disagreed. It emphasized that patent law treats published patent applications distinctly from books or traditional articles. Published patent applications are a unique category under § 102(e)(1), meaning they function as prior art based on their filing, not publication, date.
Why This Matters
This ruling reinforces how courts interpret the interplay between filing dates and patent publication dates in determining prior art for IPRs. For businesses and innovators, it underscores the importance of tracking competitive filings closely—a competitor’s earlier-filed but later-published application could undermine the validity of your patent. Filing your patent application early is crucial to minimizing the prior art that can be cited against it and avoiding the risk of losing valuable patent rights due to unnecessary delays.
Practical Lessons
- Timing is everything: The filing date of a published patent application is critical—it could qualify as prior art against your patent even before it becomes publicly accessible.
- Protect your innovations early: Delays in filing patent applications can leave your inventions vulnerable to prior art challenges. Prioritize filing as a defensive strategy.
- Monitor publications: Even abandoned applications, like Martin in this case, can pose risks in patent disputes. Stay vigilant.
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