Burden of Proof for the Existence of an Act of Infringement
The trade secret owner bears not only the burden of proof for the existence of a trade secret (see Part 1 of this article, here), but also, when asserting claims for infringement under Sections 4 and 6 of the GeschGehG, the burden of proof for the existence of an act of infringement.
Unless proven otherwise, the court presumes that the defendant has neither obtained, used, nor disclosed information in bad faith. A finding of liability can only be made if, after evaluating the parties’ entire submissions, no reasonable doubt remains as to the existence of an unlawful act. In practice, proceedings concerning solely claims for unauthorized acquisition under Section 4 (1) GeschGehG are rare. Often, the trade secret owner is unaware that a third party has come into possession of their information, let alone the specific circumstances of such acquisition. Such proceedings typically arise only when there is already suspicion based on concrete evidence. Far more common in practice are claims based on unauthorized use under Section 4 (2) GeschGehG. Here, too, Section 4 (1) becomes relevant when it must be determined whether the information was obtained through an unlawful prior act or by lawful means, such as through empirical knowledge, in-house developments, or reverse engineering. In such cases as well, the burden of presentation and proof rests with the claimant. If the claimant presents a substantiated case, an exchange of arguments and counterarguments typically follows. The trade secret owner typically faces considerable difficulties in providing evidence in this context.
Relief from the Burden of Proof in Proceedings
Prima facie evidence could provide significant relief to the trade secret owner bearing the burden of proof. It allows one to infer a specific cause or behavior from certain circumstances that point to a typical sequence of events. The opposing party is then not required to provide complete rebuttal evidence, but merely to demonstrate plausibly that, in the specific case, there is a serious possibility of a different sequence of events.
Although prima facie evidence is advantageous in theory, its scope of application in proceedings under the GeschGehG is limited. For example, the Rhineland-Palatinate Regional Labor Court (LAG) ruled that the unauthorized forwarding of a file containing extensive customer data by an employee to his or her private email account did not constitute prima facie evidence that this information had been used or disclosed to third parties (Case No. 3 SaGa 8/20). Similarly, the Higher Regional Court of Jena stated that the mere similarity of product formulations does not constitute prima facie evidence of the use of another party’s trade secrets; rather, one must assume that the similarity stems from the party’s own experiential knowledge and another party’s know-how (Case No. 2 U 896/11).
The cautious application of prima facie evidence in proceedings under the Trade Secrets Act is appropriate.
The circumstances surrounding the alleged acquisition and use of trade secrets are highly case-specific and vary considerably. Even numerous similar cases therefore do not allow reliable, evidence-relevant conclusions.
In practice, circumstantial evidence is significantly more relevant than prima facie evidence in proceedings under the GeschGehG. It, too, provides the party bearing the burden of proof with a relaxation of that burden. The court must determine whether, assuming the presented circumstantial evidence is accurate, it is convinced of the truth of the main issue. However, such a conclusion is permissible only if there are no alternative interpretations of the evidence that could reasonably be considered. The claimant must therefore present circumstances that make an unlawful use of their trade secret appear plausible. Striking similarities in product characteristics can constitute such circumstantial evidence. However, identical or very similar product characteristics can often be achieved through different formulations or manufacturing processes; they are therefore not necessarily conclusive evidence. Matches in dimensions or technical details constitute valid circumstantial evidence only if, for example, they do not conform to industry standards. In proceedings between former employers and employees, the assessment of the circumstantial evidence also regularly depends on the circumstances under which the employment relationship was terminated. An employee who was unexpectedly terminated and had to leave the premises immediately, for example, would have had little time to prepare or take documents with them.
Practice shows that the parties to the proceedings often lack sufficient technical expertise to adequately clarify the facts of the case for the court. Involving patent attorneys or technical experts can therefore significantly strengthen the argumentation.
If the claimant has presented a substantiated case regarding the possible acquisition of the technology and potential technical similarities, the defendant must in turn demonstrate the differences between the products or explain how its own product was developed. Through this rebuttal, facts often come to light during the proceedings that were previously unknown to the claimant – a consequence of the balanced distribution of the burden of presentation and the burden of proof in the proceedings. In practice, another common issue arises when the defendant asserts an interest in maintaining confidentiality regarding its development processes. The opposing party may also invoke the protections under Sections 16 -20 GeschGehG and apply for a confidentiality order.
Objections Raised by the Opposing Party During Proceedings
It is not uncommon for the opposing party to raise the objection during proceedings that they relied solely on experiential knowledge when developing or designing their product. This applies in particular to former employees who had lawful access to the information during their previous employment and later claim that their knowledge is based exclusively on their own memory. In such cases, there is no “unauthorized acquisition” within the meaning of Section 4 GeschGehG, since professional experiential knowledge may be used without restriction even after the employment relationship has ended.
However, it is impermissible to “refresh” this experiential knowledge by referring to documents, even if these were lawfully created during employment. As soon as these documents are consulted at a later date, the element of “unauthorized acquisition” within the meaning of Section 4 GeschGehG is satisfied. In such scenarios, the burden of proof inevitably rests on the former employee’s memory; accordingly, the courts scrutinize such objections with great rigor.
A decision by the Federal Court of Justice (BGH) (judgment of May 2, 2024 – Case No. I ZR 96/23) illustrates where the courts draw the line regarding memory capacity: While it is still plausible that an employee could memorize three data entries containing customer names and eight-digit passwords, this is no longer realistic for ten such data entries. In such a case, it is far more likely that the employee recorded the information rather than merely recalling it. Overall, simply relying on one’s own memory – especially when dealing with a large amount of data – has proven to be a tenable defense strategy only in rare instances.
Furthermore, the defendant may raise the defense of independent development during the proceedings, which is permissible under Section 3 (1) no. 1 GeschGehG. The holder of a trade secret is not protected against a third party independently obtaining the same information through their own discovery or creation. In this case, what arises is not merely a duplicate of the original secret, but a new secret of its own – albeit one with identical content. Even in the case of a defense based on independent development, the plaintiff must first substantiate an act in accordance with Section 4 (1) GeschGehG. If the plaintiff succeeds in doing so, the defendant bears the secondary burden of proof regarding the existence of such independent development. Here, too, the defendant may invoke Sections 16–20 of the Trade Secrets Act (GeschGehG) to protect its own trade secret.
If a former employee was involved in the development of a product, it must be demonstrated in the context of their new employment that they relied exclusively on their own experiential knowledge and did not use any written documents from their former employer. In this regard, it is advantageous for the new employer to deploy a “clean team.” This captures the former employee’s experiential knowledge and passes it on to the new employer’s separate development team without the employee having any direct influence on the product’s development. Careful documentation of this process provides evidence that only experiential knowledge was used. In practice, the use of clean teams therefore represents an effective tool for strengthening the defense.
The opposing party may also raise the defense of “reverse engineering.” The reverse engineering must have been actually performed; merely pointing out the theoretical possibility that the information could have been obtained through reverse engineering is (of course) not sufficient. The opposing party must therefore demonstrate and prove that it obtained the information specifically through reverse engineering.
In practice, however, the opposing party can often prove only that individual details or dimensions were determined – the complete extraction of all information necessary for reproduction usually proves difficult. Furthermore, certain information cannot be obtained through reverse engineering at all. For example, the processing temperature of an ingredient cannot be determined retroactively. Therefore, technical expertise is regularly required to present evidence even when a defense based on reverse engineering is raised.
Conclusion
The requirements regarding the burden of proof and the presentation of evidence in proceedings under the GeschGehG present practical challenges for trade secret holders. Although the claimant must demonstrate and prove both the existence of a trade secret and the occurrence of an act of infringement and is subject to only limited relief from the burden of proof, the evidentiary situation in GeschGehG proceedings is, on the whole, balanced.
The claimant’s difficulties in providing evidence can be resolved through the principles of secondary burden of proof. At the same time, the confidentiality interests of both parties are effectively protected by Sections 16 – 20 of the GeschGehG.
Here is once again the link to a detailed discussion of the topic in a commemorative volume article. (For those who wish to cite this work or academically challenge my arguments: Maaßen, “Burden of Proof and Presentation of Evidence in GeschGehG Proceedings,” in: Fitzner/Chamber of Patent Attorneys (eds.), Festschrift Commemorating the 125th Anniversary of the Patent Attorney Profession, Carl Heymanns Verlag, Cologne, 2025, pp. 629 ff.).