You’re a patentee starting preliminary injunction (PI) proceedings at the UPC against a potential infringer. But the defendant raises grounds of invalidity against the patent. Can you propose amendments to the claims to get your PI over the line?
It’s a deceptively simple question, but there have been divergent answers from the UPC in different cases. Now we have a definitive answer from the UPC Court of Appeal (CoA) in Onward Medical v. Niche Biomedical (CoA). And that answer is “yes, but …”.
The background
Onward is the proprietor of EP 3421081 B1, which was granted by the EPO in 2020 and was not opposed. The patent claims a system for neurostimulation of a subject, for example for transcutaneous spinal cord stimulation. The idea is to provide electrical stimulation to assist with recovery of movement for subjects with spinal cord injuries. The patentee’s commercial system is called the ARCEX®, getting CE certification in September 2025. The defendant’s system is the ExaStim®, available in some UPC countries since June 2025.
First instance – the protective letter did a job
Onward filed its application for a PI on 30 July 2025. The following day, they received a copy of a protective letter that had been filed by the defendant. This is exactly what a protective letter is for – it’s a document filed by a party who expects to be sued for a PI at the UPC under a specific patent. The main purpose of a protective letter is to avoid an ex parte PI. To be useful, the protective letter needs to explain the reasons why a PI should not be granted. For example, it can explain why the patent is not infringed, or not valid, and/or other reasons, such as a lack of urgency or necessity for the PI.
Having had sight of the contents of the protective letter, the patentee can decide that discretion is the better part of valour, and withdraw the PI application in confidence. This means that the “defendant” has no idea that their protective letter has been deployed, and has saved them from having to defend against a PI at the UPC.
In this case, the patentee did not withdraw. Instead, on 29 August 2025 they filed a series of 8 auxiliary requests (ARs) that set out various amendments to the claims of the patent. Their main request was that the PI should be granted on the basis of the unamended claims. There was a hearing in September 2025 – this was inter partes, and so the protective letter not only forced the patentee into proposing claim amendments, but also ensured that the defendant had their arguments heard in person.
The Munich Local Division (LD) issued its order in Onward Medical v. Niche Biomedical (first instance) in October 2025, refusing the PI on the grounds that they could not be sufficiently certain that the patent was valid.
Claim amendments … in summary infringement proceedings?
This is the rub. PI proceedings are about whether the patent is about to be infringed. There is no formal validity challenge, although a defence of invalidity can be raised to cast doubt on whether a PI would be safe. In turn, this means that there is no mechanism inside PI proceedings by which the claims of the patent can be amended at the UPC. In UPC-speak, there is no counterclaim for revocation that can trigger an application to amend as a defence to the invalidity attack.
There have, though, been plenty of PI proceedings that have involved “claim amendments”. In fact, the key CoA decision on claim interpretation, Nanostring v. 10x, was a PI case involving an auxiliary request. In that case, the CoA sidestepped whether it was formally admissible by jumping ahead and deciding against it on substantive grounds.
A simple way to think about auxiliary requests in PI proceedings is that they not really claim amendments. Instead, they are changes to the proposed wording of the preliminary injunction. This is because a UPC PI will not usually just identify an infringing product, but will instead have a more general scope, framed using the wording of the claims.
LD say no
Going back to the first instance decision, the LD took the view that auxiliary requests did not help the patentee’s case, on principle. They decided that the very fact that the patentee had decided to file auxiliary requests cast doubt on the validity of the patent as granted (the main request). To award a PI, the court would have to be sufficiently certain that the patent as granted was valid, rather than any narrower form of the claims that the patentee was putting forward only in the context of the PI proceedings and not as a formal amendment of the granted patent.
CoA say yes and maybe
Appealing against the decision of the LD, the patentee requested the PI based on claim 1 as granted or, in the alternative, based on a combination of claim 1 with claim 9 and some features of claim 7. This was broadly similar to AR8 filed at first instance. In the oral hearing, in reaction to the CoA preliminary view that granted claim 1 may not be valid the patentee withdrew the main request and so the “auxiliary request” amendment was being made unconditionally.
The CoA explained that the unconditional filing of an amended main claim can be done in PI proceedings. Therefore it is fine for the patentee to assert a claim scope that would be an amendment of the original claims. Also, it is OK to propose conditional amendments, i.e. auxiliary requests.
Disagreeing with the LD, the CoA decided that the issue of validity for the PI is not whether the patent as granted is valid. If the patentee is putting forward an amended claim scope, then it is that scope that is the subject of the PI proceedings, and which needs to be valid.
Should the mere filing of amendments count against the patentee’s assertion that the granted patent is valid? No. The CoA observed that this may just be sensible behaviour by the patentee, to avoid lengthy discussion about whether a broad claim is valid, when a narrower claim would just as well cover the alleged infringement.
Also, heading off another argument, the CoA explained that, because amendments can be proposed in PI proceedings, it is not necessary for the patentee to request central limitation of the patent at the EPO before launching the PI application. This would take too long to be finalised and would risk losing the required urgency for the PI to be granted.
However, there are two wrinkles. First, when should the ARs be filed? Second, how many ARs are acceptable?
When to file the ARs in PI proceedings?
The first point arises because, as mentioned above, there is no clear moment in PI proceedings inviting claim amendments – there is no specific opportunity for an application to amend. In this case, the ARs were filed in response to the protective letter invalidity arguments put forward by the defendant.
The decision makes it clear that proposing amendments in the PI application itself should be OK. With that in mind, it may be sensible for the patentee to include in the PI application a conditional request for an injunction of narrower scope than the main claim, perhaps a scope corresponding to the narrowest dependent claim that is clearly infringed.
But if the PI application does not include a narrower scope at the outset, any AR filed later is subject to admissibility checks. Formally speaking, Rule 263.1 and 2 RoP apply, because this a change of case and permission to add an AR will need an explanation as to why it would not have been made earlier and why it will not unreasonably hinder the defendant. Presumably, filing an AR in response to new prior art attacks presented for the first time by the defendant should be fine. But if the AR is responsive to attacks already seen elsewhere (e.g. in ongoing EPO opposition proceedings) then this may cause problems.
In this case, the final version of the amended claim was only filed during the appeal proceedings. The CoA allowed the amendment but said clearly that an appeal court should usually exercise restraint in admitting new ARs.
How many ARs in PI proceedings?
In main proceedings at the UPC, the patentee can file an application to amend as part of the defence to revocation. ARs are expressly allowed by the R.30 RoP, but must be “reasonable in number”. There has been massive variability in what is considered “reasonable” in different cases, with more than 80 being accepted in one case.
Clearly deciding to set down a marker, here the CoA noted that PI proceedings are intended to be summary in nature and so similarly large numbers of ARs should not be entertained. The CoA said that, as a rule, one or a small number can be regarded as appropriate. With my cautious hat on, I read that as “one, or two, or maybe three”.
What was the outcome?
Interestingly, the CoA decided not to overturn the LD’s refusal of the PI, but got to that conclusion based on different reasons. They did not reach a view on validity. The CoA decided that the amended claim would probably not be infringed, whether as direct or indirect infringement.
What’s next?
In the meantime, in December 2025, the patentee launched a full infringement action against the defendant, also in the Munich Local Division. Should the failure of the PI deter them? Well, we reported on a similar set of circumstances in UPC Weekly 2025 w23 where the patentee won on the merits having earlier failed on a PI application due to concerns about the patent’s validity. Presumably the patentee will not be wanting to put forward the same amended claims as the CoA considered were likely not infringed.
