The Rules of Procedure (RoP) distinguish between party-appointed and court-appointed experts, each governed by distinct procedural requirements. Early case law has addressed cross-examination (or its absence), “hot tubbing”, the treatment of employee witnesses, and the role of experts in evidence preservation proceedings. This article examines the rules and emerging practice.

Party-Appointed Experts

Rules

Under Rule 181(1) RoP, a party may provide any expert evidence it considers necessary, subject to orders made by the court at the interim conference (Rule 104(e)) or in preparation for the oral hearing (Rule 112.2(b)). The rules governing witnesses (Rules 175–180) apply mutatis mutandis to party experts.

A written expert statement must be signed and must include a statement that the expert is aware of the obligation to tell the truth (Rule 175). The statement must also set out any current or past relationship between the expert and the instructing party, and any actual or potential conflict of interest (Rule 175).

When a party expert is summoned to give oral evidence, the order must additionally state that: (a) the expert has a duty to assist the court impartially on matters relevant to their area of expertise, which overrides any duty to the party retaining them; and (b) the expert is to be independent and objective and shall not act as an advocate for any party (Rule 181).

The compensation for costs of party experts is based on customary rates in the respective sector, with due regard to the required expertise, the complexity of the issue, and the time spent (Rule 153).

Case Law

The court may order that an expert witness be heard in person: (a) of its own motion; (b) where a written statement is challenged by the other party; or (c) on an application by a party.

A party seeking to offer oral expert evidence shall make an application and set out: (a) the reasons why the witness should be heard in person; (b) the facts which the party expects the witness to confirm; and (c) the language in which the witness shall give evidence (Rules 176-177 and GlaxoSmithKline v Moderna).

No right to a “general hearing” of all experts. In GlaxoSmithKline v Moderna the court confirmed there is no right to a “general hearing of all experts as witnesses on their entire written statements”. GSK had sought a Rule 176 application to have five party experts (two of its own and three of Moderna’s) heard in person to “elaborate on the evidence contained in their written statements”. The court agreed with Moderna that the procedural rules do not provide for a general hearing of all experts on their entire written statements. GSK had not specified which particular facts it expected each expert to confirm, as required by Rule 176 RoP. The court noted that GSK’s attempt to introduce a “UK-style cross-examination” lacked a basis in the UPC framework. GSK had also sought to have the experts heard the day before the hearing, but the court confirmed that any expert testimony would be heard as part of the oral hearing and advised that the experts should attend, at least online, to be ready for any specific questions.

Hearing ordered where written expert opinions directly conflict. In Advanced Bionics v MED-EL the court summoned both side’s experts to appear where the written statements challenged one another. The examination was limited to the facts establishing common general knowledge at the priority date.

“Hot tubbing” of experts. In Sanofi v Accord two experts were ordered to be heard in person on factual issues relating to inventive step and the reasonable expectation of success. In the expert summons, the judge-rapporteur specified several questions to be answered and provided a schedule requiring the experts to be questioned together in a “hot tub” format first by the panel and then by the parties.

Inventors cannot serve as party experts. In Advanced Bionics v MED-EL the inventor of the patent in suit was not permitted to be heard as either an expert or a witness. The Paris CD held that, as inventor, he may have a direct interest in the outcome of the case and therefore did not meet the requirements for impartiality, objectivity, and independence under Rules 181(2)(a) and (b).

Employees treated as witnesses, not experts. In Michelin v Goodyear the court treated Dr Poulbot (a Michelin employee) as a “witness” rather than an expert, noting that Michelin’s own representative had conceded the point at the hearing. The same treatment was applied to Mr Van Tuijl, a former Goodyear employee. The court considered their written statements to be “valuable technical information”, but not carrying the probative value of independent and objective expert evidence.

Cross-examination and questioning practices. Cross-examination is not standard practice at the UPC. The current approach to expert examination reflects varied national traditions. For example, oral expert examinations are routine in Germany but less common in France, and cross-examination as practised in England or in arbitration does not appear to be taking hold at the UPC.  Where experts have been heard, the court has generally preferred judge-led questioning.

Court-Appointed Experts

Rules

Under Article 57 UPCA and Rule 185(1) RoP, where the court must resolve a specific technical or other question, it may of its own motion, and after hearing the parties, appoint a court expert. The parties may make suggestions regarding the identity of the expert, their technical background, and the questions to be put to them (Rule 185(2)). The court expert must possess the requisite expertise, independence and impartiality, and the parties are entitled to be heard on these matters (Rule 185(3)).

The appointment is made by order specifying, among other things: (a) the expert’s name and address; (b) the facts of the action; (c) the questions put to the expert; (d) the time period for the report; and (e) information about sanctions and duties (Rule 185(4)). The expert must confirm in writing that they will present the report within the specified time (Rule 185(6)). The Court agrees a fee with the expert, which may be reduced if the report is late or of insufficient quality (Rule 185(7)).

If the expert fails to present their report within the specified (or extended) time, the court may appoint a replacement and hold the defaulting expert liable for costs (Rule 185(8)). The Registry maintains an indicative list of technical experts (Rule 185(9)).

A court expert must: (a) present a written report within the specified timeframe; (b) remain under the supervision of the court; (c) give advice only on questions put to them; (d) not communicate with one party without the other being present or consenting (documenting all communications in the report); (e) not disclose the report contents to third parties; (f) attend the oral hearing if requested and answer questions of the court and the parties; and (g) maintain an overriding duty to assist the court impartially (Rule 186). Once the report is presented, the parties must be invited to comment on it in writing or at the oral hearing (Rule 187).

Case Law on Court Experts

Requests for court experts have largely been refused. In Meril v Edwards Meril requested the appointment of a court expert, the obtaining of an expert report, and the summoning of that expert and its own party experts to the oral hearing. The Court of Appeal upheld the judge-rapporteur’s order dismissing all the requests.

Post-hearing appointment rejected. In Centripetal v Keysight the claimant’s request to reopen the oral hearing and appoint an expert for review of the source code of the alleged infringement was rejected. The court found no exceptional circumstances justifying the reopening, noting that the claimant had failed to explain why it had not sought this evidence earlier in the proceedings.

Experts in Evidence Preservation and Inspection

A significant area of expert involvement at the UPC has been in evidence preservation (saisie) and inspection proceedings under Rules 192–199 RoP. Under Rule 196(4) and (5), the person carrying out preservation measures must be a professional person or expert guaranteeing expertise, independence, and impartiality. In practice, the court often appoints patent attorneys as experts for trade fair inspections and evidence preservation (LiNA v Tonglu). Strict confidentiality obligations are imposed on the expert and bailiff, preventing disclosure to the applicant or third parties until a release order is issued (LiNA v Tonglu).

Expert Impartiality in Evidence Preservation

In Topsoe v SYPOX the court considered an application to challenge the appointed experts on grounds of bias. The court established that there is cause for concern regarding an expert’s impartiality if, from the perspective of a knowledgeable and reasonable observer, certain circumstances give rise to justified doubts as to the expert’s impartiality or independence. However, the court held that the content of the expert’s report alone is not sufficient to cast doubt on impartiality. Even a flawed report or lack of expertise does not necessarily indicate bias; rather, there must be circumstances indicating a lack of objectivity. In that case, the challenge was rejected on the facts.

The court also noted that a professional relationship between the applicant’s patent attorneys and the appointed expert does not per se give rise to doubts as to the expert’s independence - though any difficulties that arise regarding the later admissibility of the detailed description fall at the expense of the party that nominated the expert (Komax v Jiangsu).

Experiments Ordered by the Court

Under Rule 201, the Court may order experiments to prove a statement of fact, on a reasoned request by a party. The party must: (a) identify the facts to be established; (b) describe the proposed experiments in detail; (c) propose an expert; and (d) disclose any previous attempts at similar experiments. Unless otherwise ordered, the requesting party initially bears the costs (Rule 201(4)). The order will specify the: (a) expert’s name; (b) time period; (c) conditions; and (d) the format for the report. Once the report is presented, the parties are invited to comment, and the expert may be summoned to the oral hearing (Rule 201(7)).