CAFC Clarifies Doctrine of Equivalents and Injunction Standards in Wonderland v. Evenflo
Plus, the "Dracula Project" Emails
In a recent Federal Circuit decision touching on the Doctrine of Equivalents, claim construction for integral parts, and the evidentiary standards for permanent injunctions, the panel delivered a mix of concurrences-in-part and dissents-in-part in Wonderland Switzerland AG v. Evenflo Company, Inc., Nos. 23-2043, 23-2233, 23-2326 (Fed. Cir. Dec. 17, 2025).
The precedential opinion offers guidance for patent practitioners, particularly regarding how strictly courts will enforce claim limitations regarding the location of mechanical components and the high evidentiary bar required to prove irreparable harm. The case also featured emails about car-seat technology using a vampiric codename.
The court affirmed findings of infringement regarding one patent but reversed a finding of infringement under the Doctrine of Equivalents (DOE) for another. Notably, the panel also vacated a permanent injunction due to speculative evidence of harm and ordered a new trial on willfulness after finding the district court erroneously excluded a highly probative email chain referencing a “Dracula Project.”
Background of the Dispute
The litigation centers on child safety seats. Wonderland Switzerland AG (”Wonderland”), the exclusive supplier for Graco Children’s Products, sued Evenflo Company, Inc. (”Evenflo”) in the District of Delaware.
Wonderland alleged that several of Evenflo’s convertible car seat models—specifically the “4-in-1” (EveryFit, EveryKid) and “3-in-1” (SafeMax, Evolve, Transitions) seats—infringed U.S. Patent Nos. 7,625,043 and 8,141,951.
The ’043 patent covers a car seat with a “seat back having a locking mechanism” that allows it to detach from the seat base. The ’951 patent describes a safety seat with a movable backrest and specific engaging mechanisms.
Following a trial, a jury found that Evenflo’s products infringed claim 1 of the ‘043 patent under the Doctrine of Equivalents and infringed claims of the ’951 patent both literally and under the DOE.
The jury also found the infringement of the ’043 patent was not willful. The district court subsequently denied Evenflo’s motion for Judgment as a Matter of Law (JMOL) and granted a permanent injunction against Evenflo.
The Court’s Analysis
The Federal Circuit’s opinion serves as a reminder that specific structural limitations in claims cannot be easily circumvented or satisfied through the Doctrine of Equivalents.
The Limits of the Doctrine of Equivalents
The most significant reversal concerned the ’043 patent. Claim 1 explicitly requires “a seat back having a locking mechanism for selectively detachably connecting said seat back to said seat assembly.”
In Evenflo’s accused 4-in-1 seats, the locking components (hooks, handles, springs) were located on the seat assembly (the base), not the seat back. The seat back merely contained a stationary metal bar (“lock rod”).
The jury found infringement under the Doctrine of Equivalents, presumably accepting the argument that the arrangement was substantially the same. The Federal Circuit disagreed.
Chief Judge Moore, writing for the majority (joined by Judge Prost), emphasized that the DOE applies to individual elements, not the invention as a whole. Because the claim required the mechanism to be on the seat back, placing it on the seat assembly was not equivalent.
‘[DOE] must be applied to individual elements of the claim, not to the invention as a whole’ ... We conclude there can be no equivalence as a matter of law with Evenflo’s 4-in-1 seats, which do not include any elements on the seat back for selectively detachably connecting the seat back to the seat assembly.” (Opinion, p. 6, citation omitted).
“Connected To” and Integral Structures
Regarding the ‘951 patent, Evenflo argued it could not infringe the limitation of a “pulling member connected to the connecting member” because, in its products, those two parts were molded from a single piece of plastic. Evenflo contended that “connected to” implies two physically separate pieces joined together.
The court rejected this rigid distinction. Relying on the specification, which described distinct portions formed integrally, the court held that two functional parts of a single integral structure can indeed be “connected to” one another.
The High Bar for Permanent Injunctions
The Federal Circuit vacated the permanent injunctions for both patents. For the ’951 patent, the reversal was straightforward: Wonderland had expressly declined to request an injunction for that patent. For the ’043 patent, the court found the district court abused its discretion by relying on “speculative and conclusory evidence” of irreparable harm.
Wonderland had argued that lost car seat sales would lead to lost sales of other products due to brand loyalty and that Evenflo’s infringement harmed its reputation as an innovator.
The Federal Circuit found the record lacked concrete data to support these theories. Testimony that a parent “may” buy other products or that consumers “might” blame the technology was insufficient.
The “Dracula” Emails and Willful Infringement
In a significant win for Wonderland on cross-appeal, the court ordered a new trial on willfulness for the ’043 patent. The dispute involved an internal email chain from Evenflo’s affiliate titled “Dracula Project.”
In the emails, employees identified that a product might fall within the scope of the ’043 patent and explicitly asked: “could you pls advise HOW US avoid the claims of the patent ingeniously?”
The district court excluded this evidence under Federal Rule of Evidence 403, fearing it would confuse the jury because it referenced a project (”Dracula”) not directly at issue.
The district court excluded this evidence under Federal Rule of Evidence 403, citing risks of jury confusion and potential privilege issues. The Federal Circuit reversed this ruling, finding it an abuse of discretion.
Crucially, the panel clarified that these were not privileged communications. The panel noted that the email chain’s mere reference to a “lawyer letter” was insufficient to invoke attorney-client privilege. The court reasoned that any sensitive references could simply be redacted, rather than excluding the entire highly probative chain.
Judge Reyna dissented on this specific issue, arguing that the district court properly exercised its discretion in excluding the emails to prevent jury confusion. However, the majority concluded that any confusion, like confidential/sensitive information, could be managed with redactions rather than total exclusion.
Key Takeaways and Practical Implications
This decision provides several actionable insights for IP professionals.
1. Drafting and Claim Strategy: Location Matters
The reversal on the ’043 patent underscores the danger of overly specific structural limitations. By claiming a “seat back having a locking mechanism,” the patentee inadvertently excluded designs where the mechanism resides on the mating part. Practitioners often draft claims that focus on the interaction between components rather than rigidly assigning active mechanisms to one side of an interface, or include dependent claims covering alternative configurations.
2. “Connected To” is Broad
The affirmation regarding the ’951 patent confirms that the phrase “connected to” does not necessarily require separate parts. This is a key interpretation for modern manufacturing, where multiple functional components are often injection-molded (or 3D printed) as a single unit. Defendants cannot easily escape infringement claims simply by integrating multiple parts into a unitary structure if the functions remain distinct.
3. Injunctions Require Hard Data
The vacatur of the injunction serves as a strict warning: theories of market harm are not evidence. To secure a permanent injunction, a plaintiff must provide non-speculative proof that the infringement caused specific, unquantifiable loss. General assertions that “brand loyalty” drives cross-product sales, or that infringement dilutes “market allure,” will likely fail without supporting data or consumer surveys.
4. The Risk of Internal Communications
The admission of the “Dracula” emails highlights the discoverability risks inherent in product development. Use of phrases like “avoid the claims... ingeniously” can be devastating in a willfulness inquiry. In-house counsel must educate engineering teams on professional communication. While designing around patents is a legitimate business activity, the language used to describe that process can be easily weaponized to suggest a willful disregard for IP rights.
Practitioners should also remind clients that privilege is not automatic; simply copying an attorney on an email chain like the ‘Dracula’ thread may not shield it from discovery. Instead, specific inquiries regarding patent scope or validity should be formally directed to counsel for the express purpose of obtaining legal advice.
Conclusion
Wonderland v. Evenflo reinforces the Federal Circuit’s commitment to precision in claim analysis and rigor in evidentiary standards. The decision limits the reach of the Doctrine of Equivalents, preventing it from effectively rewriting clear structural requirements. Simultaneously, it demands that plaintiffs seeking injunctive relief move beyond theoretical harm to prove actual injury.
Perhaps most importantly for litigation strategy, the ruling on the “Dracula” emails signals that the Federal Circuit will not allow Rule 403 to shield defendants from highly probative evidence of willfulness, even if that evidence carries some risk of prejudice.
As technology evolves and manufacturing methods integrate more functions into fewer parts, the court’s pragmatic approach to integral structures offers an interesting adaptation of patent law to modern industrial design.
Disclaimer: This is provided for informational purposes only and does not constitute legal or financial advice. To the extent there are any opinions in this article, they are the author’s alone and do not represent the beliefs of his firm or clients. The strategies expressed are purely speculation based on publicly available information. The information expressed is subject to change at any time and should be checked for completeness, accuracy and current applicability. For advice, consult a suitably licensed attorney and/or patent professional.