Behind the factory door: how far can a UPC saisie reach?

Sometimes proving patent infringement is simple. You buy the product, take it apart and compare it with the claims. Often you can’t. The patent may cover a manufacturing process, a production step inside a factory, software running on internal servers, or a product whose relevant features can’t be worked out from the finished article. In those cases, the evidence needed to prove infringement usually exists only on the alleged infringer’s premises and systems. The patent holder may have good reason to suspect infringement and still have no way of proving it in court.

The Unified Patent Court (UPC) has several legal tools for this situation. The most far-reaching is the order to preserve evidence under Article 60 of the Agreement on a Unified Patent Court (UPCA). It is commonly called a saisie, after the French saisie-contrefaçon it is modelled on. Swedish readers might recognise the concept from the national intrångsundersökning. The UPC Court of Appeal has recently spoken out about what a saisie may and may not cover, in their decision dated 3 September 2026, in the case WEPA v Essity (UPC_CoA_113/2026).

What a saisie is

A saisie is a court order that lets a patent holder secure evidence of an alleged infringement before the evidence can disappear, typically before the infringement action itself is filed. The applicant must present the evidence reasonably available to it to support the claim that the patent has been, or is about to be, infringed. Full proof is not required at this stage. Under Article 60 UPCA, the order may authorise:

a detailed description of the allegedly infringing products or processes, with or without taking samples;
the physical seizure of allegedly infringing products and, in appropriate cases, of the materials and tools used to make or distribute them, and related documents;
an inspection of premises.

The order is carried out by a bailiff, a public enforcement officer who executes the court’s order on site. The bailiff is usually accompanied by a court-appointed expert, an independent technical specialist who examines what is found and writes a report for the court. The court decides in each case whether representatives of the patent holder may attend, and under what conditions.

A saisie can be granted ex parte, meaning without first hearing the alleged infringer. This is allowed in particular where delay is likely to cause irreparable harm to the patent holder, or where there is a demonstrable risk that evidence will be destroyed. Surprise is the point: the defendant is notified when the order is executed at the latest, and can then ask the court to review it. The court may require the applicant to provide security for any damage the measure causes. It can also make arrangements to protect the defendant’s confidential information in the evidence collected.

The saisie is only a preparatory step. Under Article 60(8) UPCA, the applicant must start proceedings on the merits (the actual infringement action) within 31 calendar days or 20 working days, whichever is longer. Otherwise the defendant can ask the court to revoke the measures.

The case: WEPA v Essity

Essity holds a European patent on tissue paper containing pulp fibres from Miscanthus, a grass. On 17 April 2026, the Hague Local Division granted Essity an ex parte order to preserve evidence at WEPA’s premises, and the order was executed on 21 April. WEPA appealed. The Court of Appeal’s decision affects how future applications should be drafted.

1. The scope of a saisie is not limited to technical evidence. Article 60 covers ”any relevant evidence in respect of the alleged infringement”. The Court confirmed that this includes evidence of infringing acts found in promotional and commercial documents, not only technical documentation about the product or process. For a patent holder, material such as brochures, sales documentation and customer-facing information can be as relevant to the infringement case as a description of the production line.

2. The bailiff and the expert may not interview the defendant’s staff. The Court held that Article 60 gives the UPC no power to authorise a bailiff or court expert to question the defendant’s personnel on technical details of its products or production processes. The court can, however, order the defendant to have its staff provide practical information needed to carry out the order, such as passwords to reach digital data. If statements from personnel are needed at all, they must be taken under the court’s own control, through the means of evidence in Article 53 UPCA, which include hearing parties and witnesses with the safeguards of court proceedings.

The Hague order had stated that staff were not obliged to answer. The Court held that this did not solve the problem, because staff faced with a bailiff acting under a court order could reasonably believe they had to answer.

This had real consequences. All copies of the expert’s report must be destroyed and the report redrafted within two weeks, leaving out staff answers to substantive questions and any findings that rest solely on those answers. Findings based on other material may stay. The deadline for Essity to start the merits action under Article 60(8) runs from the redrafted report.

3. A prior use defence does not, as a rule, block a saisie. A right of prior use lets a party that was already using an invention in good faith before the patent’s filing or priority date continue that use. Under Article 28 UPCA, this is governed by the national law of each member state. WEPA argued that it had such a right. WEPA had first raised the argument on appeal, so it was inadmissible. The Court still stated the principle: Where preserving evidence is necessary for the applicant to bring an infringement action, the applicant’s interest generally prevails. Prior use is to be decided in the infringement action itself. A saisie should be refused on this ground only where a summary examination shows clearly that the infringement action has no prospect of success. A summary examination is a brief, provisional assessment, not a full trial of the issue.

The CoA took a similar approach to validity. A granted patent is presumed valid. Here, the EPO Opposition Division had maintained the patent as granted, which confirmed that presumption. WEPA had appealed that decision and brought a separate revocation action, but the Court held that ”those uncertainties and disputes” were not enough to deny Essity the right to preserve evidence. The picture may be different where an Opposition Division decision clearly calls validity into question.

This confirms earlier decisions

Two earlier Court of Appeal decisions point the same way:

In Centripetal v Palo Alto (28 May 2025), the Court overturned a first-instance refusal. It held that the applicant had met the standard of presenting reasonably available evidence of infringement.
In Polytechnik v Dall (29 June 2026), the Court applied a comparable standard to orders to produce evidence under Article 59 UPCA. With such an order, the court can require a party to hand over specified evidence under its control. The requesting party must present reasonably available and plausible evidence, but does not need full proof. The evidence requested must also be strictly necessary and proportionate, and a request made to explore or speculate will be refused.

The direction is consistent. It is comparatively easy to obtain an evidence measure at the UPC, but the court keeps tight control over what the measure may actually be used for.

What this means in practice

If you are a patent holder considering a saisie:

Collect the evidence you can reasonably get beforehand, so that infringement is plausible to the court.
Define the evidence sought broadly enough to include commercial and promotional documents, not only technical material.
Say precisely which documents, data sources and systems the order should cover, including the practical cooperation needed to reach them, such as access credentials.
Don’t rely on questioning the defendant’s employees. If witness evidence is needed, plan to obtain it through the court under Article 53 UPCA.
Make note of the Article 60(8) deadline for starting the merits action from the start.

If your company could face a saisie:

Consider filing a protective letter with the UPC. It puts your arguments before the court in advance if an ex parte application is filed against you.
Have an internal procedure for the arrival of a bailiff: who receives them, and which counsel to call immediately.
Cooperate with the order as drafted, including giving the practical access information it requires. Following WEPA v Essity, the order cannot authorise the bailiff or expert to question your staff on technical matters.
Read the order carefully to check its scope, and consider asking the court to review it and to protect your confidential information.
Raise every defence, including any prior use right, at first instance. Arguments first raised on appeal risk being inadmissible.

In short, the order should be drafted to secure documents and data, not conversations.

How Brann can help

Brann advises clients on both sides of UPC evidence proceedings. We prepare applications for the preservation and production of evidence, and we help companies prepare for, and respond to, measures ordered against them. Please get in touch with us to discuss your situation.

This article is a general overview and does not constitute legal advice. Every case turns on its own facts.

Prepared by Lennard Mooij, European Patent Attorney and Partner at BRANN AB