Yangtze Memory Technologies Co., Ltd. v. Micron Technology, Inc., Micron Europe Ltd., Micron Semiconductor (Deutschland) GmbH, Micron Semiconductor France SAS

This procedural order was issued by the Düsseldorf Local Division of the Unified Patent Court in proceedings concerning European Patent No. 3 909 047. The Claimant is Yangtze Memory Technologies Co., Ltd., a Chinese company based in Wuhan, Hubei. The Defendants are four Micron entities: Micron Technology, Inc. (USA), Micron Europe Ltd. (UK), Micron Semiconductor (Deutschland) GmbH (Germany), and Micron Semiconductor France SAS (France). The Claimant alleges that the Defendants infringe EP 3 909 047.

The dispute centers on procedural fairness and the timing of new arguments. On 20 July 2026, the Defendants submitted their Rejoinder, in which they introduced for the first time two new lines of argument: (1) a prior use right defence based on a different die, the Z01M die, supported by newly filed Exhibit BP 12; and (2) an assertion that the so-called 'internal mode' is deactivated in the normal functioning of the Y2BM die.

The Claimant filed an application on 25 August 2026 seeking either to have these new arguments disregarded as belated under Rule 9.2 RoP, or alternatively to be granted permission to file further written pleadings under Rule 36 RoP to respond to the new arguments.

The Defendants countered that the new arguments were not belated. They argued that the Claimant's initial infringement mapping on the Y2BM die in the Statement of Claim was inconclusive, and that the Claimant only introduced the 'alternative path' and the concept of an 'internal mode' of operation for the first time in its Reply. According to the Defendants, this prompted them to investigate further and raise the new defences in their Rejoinder. The Defendants also argued that even if the arguments were considered late-filed, disregarding them would be disproportionate, and that granting the Claimant another written submission would be inequitable since the Claimant had the opportunity to present its case from the beginning.

The Presiding Judge Thomas, acting as judge-rapporteur, addressed the Claimant's requests in turn. Regarding the request to disregard the Defendants' new arguments as belated, the court held that this assessment requires an in-depth analysis that can only be made with certainty during or at the end of the oral hearing. The judge-rapporteur therefore exercised discretion to postpone the decision on these issues until after the oral hearing at the latest, citing prior UPC case law. Consequently, the second request — seeking to prohibit the Defendants from relying on these arguments at the oral hearing — was bound to fail from the outset.

However, because the Defendants' submissions had not been rejected at this stage, the court proceeded to address the alternative request under Rule 36 RoP. The court found that the Claimant's request for permission to submit a further written pleading was justified in light of the principles of due process, fairness, equity, efficiency, and the right to be heard. The court noted that it was undisputed that both new arguments first appeared in the Rejoinder, and that without further pleading, the Claimant would have no opportunity to respond in writing. Admitting the further written pleading was characterized as a precautionary measure in case the Court ultimately does not reject the new factual submissions as belated.

The court ordered that: (1) the decision on the rejection of the Defendants' new arguments regarding the Z01M die prior use right, the 'internal mode' of the Y2BM die, and Exhibit BP 12 shall be deferred, with the Panel ruling on this request during or following the oral hearing if necessary; and (2) the Claimant is given the opportunity to respond in writing to the Defendants' new arguments regarding the alleged prior use right arising from the Z01M die by 17 September 2026.