When Internal Employee Emails Turn Costly - Patent Willfulness Lessons

In Wonderland Switzerland AG v. Evenflo Company, Inc., the Federal Circuit reaffirmed a point that patent litigators routinely argue but courts do not always enforce consistently: internal employee emails that recognize infringement risk and discuss how to avoid patent claims are often among the most probative evidence of willful infringement. When such evidence is excluded wholesale under Federal Rules of Evidence Rule 403 as unfairly prejudicial, appellate scrutiny may be unforgiving and result in reversal and remand/reconsideration, significantly escalating the cost of litigation and the potential for treble damages and attorney’s fees.

The case reached the Federal Circuit after a jury found infringement but declined to find willfulness. Wonderland sought a new trial on willfulness, contending that the district court improperly excluded an internal email chain. Those emails, sent by an employee of an affiliated company to Evenflo personnel, referenced the asserted patent, flagged that an Evenflo product “might fall under” the scope of a specific claim, and asked how to “avoid the claims of the patent ingeniously.” The district court excluded the emails based on concerns about jury confusion and unfair prejudice. The Federal Circuit reversed.

Willfulness, the court reiterated, is not established by mere knowledge of a patent. The question is whether the accused infringer acted despite a known or obvious risk of infringement. The excluded emails directly addressed that inquiry. They reflected internal recognition of claim scope, identification of a potentially infringing product, and an effort to navigate around the claims. That combination, the court held, goes well beyond background knowledge and squarely into subjective intent. The court explained:

The messages . . . are clearly probative of willfulness, and they are not merely cumulative of Evenflo’s stipulation to awareness of the ’043 patent. . . . Here, the messages go beyond knowledge by demonstrating Evenflo was aware one of its accused 3-in-1 seats—the Evenflo Evolve—was at risk of infringement and that its affiliate sought advice from Evenflo on how to “ingeniously” avoid the claims of the ’043 patent.

The Federal Circuit rejected the notion that Rule 403 justified exclusion of this evidence. While acknowledging district courts’ broad discretion, the court emphasized that Rule 403 is not a mechanism for cleansing the record of damaging intent evidence. The emails were highly probative, and any legitimate concerns about confusion could have been handled through redactions or limiting instructions. Excluding the core communications altogether was an abuse of discretion.

The court also disposed of hearsay and privilege objections. The emails were not offered to prove actual infringement, but to show notice and state of mind, placing them outside the hearsay bar. In addition, a passing reference to seeking legal advice did not render the communications privileged, particularly where targeted redactions could address any concern.

The Federal Circuit concluded that the exclusion of the emails was not harmless, and removing some of the most probative email evidence from the jury’s consideration materially impaired Wonderland’s case. The court therefore ordered a new trial limited to willfulness, reopening the possibility of enhanced damages and attorney fees.

Overall Observations and Lessons

The Wonderland Switzerland AG v. Evenflo decision carries clear lessons for patent disputes. Knowledge of a patent alone rarely supports willfulness, but documented awareness of infringement risk frequently does. Emails that map claim language onto products and discuss design-around strategies are precisely the type of evidence that are highly relevant.

Wonderland underscores the importance of internal communications and framing them as state-of-mind evidence rather than technical proof. Anticipating Rule 403 challenges and proposing redactions or limiting instructions early can be decisive. For companies, the message is more cautionary: internal patent discussions are not informal or disposable. They are often the most relevant evidence of willfulness claims.

In short, Wonderland confirms that what employees say internally about patent risk can determine whether an infringement case ends with compensatory damages—or escalates to treble damages and attorney fees.

Practical Tips

For Patent Prosecutors

• Draft with internal scrutiny in mind. Claims and specifications that map cleanly onto product features are easier for engineers to analyze. Clear scope is valuable, but prosecutors should be mindful that internal claim-mapping by competitors can become willfulness evidence.
• Counsel clients on document hygiene. Prosecutors are often the first patent professionals clients interact with. Reminding clients that internal patent discussions are not privileged by default can prevent avoidable willfulness exposure.
• Internal employee communications/statements matter. Arguments emphasizing broad functional coverage or ease of infringement can later be cited as justification for perceived infringement risk. Prosecutors should counsel clients to avoid these types of communications before a full analysis.

For Patent Litigators

• Treat emails as core willfulness evidence, not background noise. Willfulness cases are frequently won in discovery, not at trial. Internal communications identifying claim scope and risk are often more persuasive than expert testimony.
• Frame intent, not technical truth. Emails should be offered to show notice and state of mind, avoiding hearsay pitfalls.
• Anticipate Rule 403 early. Proactively proposing redactions and limiting instructions can neutralize exclusion arguments and preserve key evidence for the jury.
• Leverage enhanced-damages pressure. Even the realistic possibility of treble damages and attorney fees materially shifts settlement dynamics once credible willfulness evidence is in play.

is a partner in Manatt, Phelps and Phillips’ Intellectual Property Protection and Enforcement business unit and is the author of Patent Prosecution: Law, Practice, and Procedure, 2025 Edition, and Constructing and Deconstructing Patents (2d Edition).

Wonderland Switzerland AG v. Evenflo Company, Inc., 162 F.4th 1346, 2025 USPQ2d 247670, 2025 WL 3648495 (Fed. Cir. 2025).

Id., 162 F.4 at 1360.

Id., 162 F.4th at 1359.

Id., 162 F.4th at 1361.