On August 20, 2025, the U.S. District Court for the District of Delaware (court) found inequitable conduct when Applicant, Lindis Biotech, GMBH (Lindis), relied on data from hastily performed experiments to obtain a patent from the United States Patent and Trademark Office (USPTO), while withholding from the USPTO more thorough contradictory data. In view of the evidence presented, the court concluded that the only reasonable inference was that the data were withheld to deceive the USPTO. This conclusion supported a finding of inequitable conduct, rendering the subject patent unenforceable. This case serves as a reminder that individuals involved in the prosecution of a patent application (including inventors) have a duty to disclose material information to the USPTO, including pre- or post-filing experiments that contradict experiments relied on during prosecution of the patent application.
Background
Inventors, patent attorneys, applicants, and anyone associated with patent prosecution have duties of candor, good faith, and disclosure to the USPTO under Rule 56.1 Breach of any of these duties may constitute inequitable conduct. Importantly, inequitable conduct for a single claim renders an entire patent, and potentially the entire patent family, unenforceable, regardless of whether the patent is otherwise valid.2
To prove inequitable conduct, a party must show that the accused party:
- either withheld material information from the USPTO or committed affirmative egregious misconduct; and
- did so with specific intent to deceive the USPTO.2
Regarding the first element, withheld information is deemed “material” if it is more likely than not that the disclosure of such information would have prevented the patent from issuing.3 Affirmatively egregious misconduct typically involves deliberately making a false statement to the USPTO.4 However, mere nondisclosure of material information does not constitute affirmative egregious misconduct.2
The second element, specific intent to deceive the USPTO, requires clear and convincing evidence that the accused party:
- knew of the information;
- knew it was material; and
- made a deliberate decision to withhold the information from the USPTO.5
Intent to deceive the USPTO must be the single most reasonable inference concludable from the evidence.6 A person’s pattern of lack of candor is relevant to such an inference.7
Case Summary
In Lindis Biotech, GMBH v. Amgen Inc.:
- Lindis filed a patent application with data from hastily performed experiments;
- the inventor knew that more thorough experiments unambiguously proved the data from the hastily performed experiments incorrect;
- the inventor failed to disclose the thoroughly performed experiments and resulting data to the USPTO; and
- the subject patent was obtained based on arguing that data from the hastily performed experiments were “surprising.”
Element 1 – Materiality
Regarding the first element, the withheld results from the thorough experiments were deemed “material” because, more likely than not, a reasonable examiner with access to these results would have rejected the patented claims for lack of written description (as the claimed invention did not work as described) and obviousness (as the results of the hastily performed experiments were only “surprising,” as argued, because they were erroneous). However, the inventor’s mere nondisclosure did not rise to the level of affirmatively egregious misconduct because the inventor neither falsified data nor knowingly made false statements.
Element 2 – Specific Intent to Deceive
Concerning the second element, by clear and convincing evidence, the court concluded that the only reasonable inference was that the inventor acted with a specific intent to deceive the USPTO. Here, the inventor admitted he knew of the contradictory results of the thorough experiments and made a deliberate decision to withhold the results from the USPTO by not submitting the information in an information disclosure statement, satisfying the first and third prongs of the specific-intent inquiry.
Regarding the second prong of the specific intent inquiry, to support the contention that the inventor did not know the results of the thorough experiments were material, Lindis argued that the inventor believed that disclosing the hastily performed experimental data was good enough to satisfy his duty to the USPTO, and that the data from the thorough experiments were cumulative. The court disagreed and inferred from circumstantial evidence that the inventor knew that data from the thorough experiments were material. Specifically, the inventor conducted the thorough experiments solely to verify the hastily performed experiments and thus knew that the results from the thorough experiments were more reliable than the data submitted to the USPTO. In fact, Lindis submitted the data from the thorough experiments to the European Medicines Agency for regulatory approval but did not submit the same data to the USPTO. Therefore, by clear and convincing evidence, the most reasonable inference to be drawn from the evidence was that the inventor knew the results of the thorough experiments were material and intended to deceive the USPTO by withholding the information.
In view of the above findings, the court concluded that the inventor committed inequitable conduct, thus rendering the patent unenforceable.
Implications and Conclusion
The Lindis case is a reminder that inequitable conduct can render a patent unenforceable when a person with a duty of disclosure to the USPTO, such as an inventor, fails to disclose material information.
To avoid a finding of inequitable conduct, inventors and others with the duty of disclosure (e.g., patent counsel and anyone associated with patent prosecution, including applicants and assignees) should ensure that the USPTO is informed of any material information of which they are aware. Companies who utilize patent counsel should keep their counsel abreast of material information and submit such material information to the USPTO. Nonlimiting examples of material information include references (e.g., patents or publications), prior public uses, prior sales or offers for sale, information casting doubt on the named inventorship, experimental results conflicting with application data or arguments, U.S. applications or patents that could serve as a double patenting reference, and positions the applicant has taken that contradict those taken before the USPTO, such as contradictory statements to the Food and Drug Administration to obtain approval. If material information is confidential, clients should discuss with their patent counsel options for maintaining confidentiality while satisfying the duty of disclosure.
Importantly, all parties’ duties of disclosure and candor persist until issuance of the patent. Following patent issuance, if an applicant becomes aware of material information that was not submitted but should have been submitted to the USPTO prior to issuance, a timely and proactive Supplemental Examination may inoculate a patent from a finding of inequitable conduct.
While this case may be subject to further legal procedures, it serves as an important reminder that all individuals associated with patent prosecution have duties of disclosure and candor to the USPTO, which include the duty to disclose all information material to patentability.
For questions regarding patent strategies, please contact any member of Wilson Sonsini’s Patents and Innovations practice.
[2] Therasense, Inc. v. Becton, Dickinson & Co., 649 F.3d 1276, 1288-90, 1292-1293 (Fed. Cir. 2011).
[3] This standard is also known as “but-for” materiality. Ohio Willow Wood Co. v. Alps S., LLC, 813 F.3d 1350, 1357 (Fed. Cir. 2016). Information that is cumulative with other information already disclosed to the USPTO is not material for purposes of inequitable conduct. Regeneron Pharms., Inc. v. Merus N. V., 864 F.3d 1343, 1350 (Fed. Cir. 2017).
[4] Refac Int', Ltd. v. Lotus Dev. Corp., 81 F.3d 1576, 1583 (Fed. Cir. 1996).
[5] Belcher Pharms., LLC v. Hospira, Inc., 11 F.4th 1345, 1353 (Fed. Cir. 2021).
[6] Thus, direct evidence of intent is not required, as such evidence is too rare. Rather, a court may infer intent to deceive from circumstantial evidence. However, such an inference must be the single most reasonable inference because the clear and convincing standard of element (2) is high. See Therasense, 649 F.3d at 1290.
