Draft Arbitration Rules of PMAC: Interim Measures

On 4 June 2025, the Patent Mediation and Arbitration Centre (the Centre) of the Unified Patent Court (UPC) launched a (now closed) public consultation to gather feedback on its Draft Arbitration Rules (the Draft Rules). Building on our previous analysis, this blog post focuses on the Draft Rules’ provisions on interim measures. The Draft Rules expand on the accepted authority of arbitral tribunals to grant interim measures. With reference to the relevant provisions of other major arbitration rules, we explore what the Draft Rules offer parties seeking urgent protection for their patent rights, and what risks parties face when agreeing to these rules.

The relevant provisions for interim measures are set out in Art 26 of the Draft Rules, which defines them as temporary decisions granted before a final ruling on a dispute’s merits (Art 26(2)). Urgent relief is, of course, highly important in patent disputes, in particular in the pharmaceutical and life science space where rapid developments, such as the market entrance of a competitor using a patented product, can cause irreversible harm before a court can issue a final decision. Similarly, temporary decisions seeking to protect parallel main proceedings in different jurisdictions regarding standard-essential patents have recently also made headlines. 

As under most arbitration rules, parties conducting arbitration under the Draft Rules are free to seek interim measures before any competent court or before the tribunal, and, in appropriate circumstances, even before both in parallel (Art 26(7)). 

The Draft Rules provide the tribunal with broad discretion as to the kind of measures it can order, encompassing any measure (whether prohibitive or mandatory) it deems “appropriate”, including orders maintaining the status quo, preventing harm to the arbitration process, preserving assets, or safeguarding relevant evidence (Art 26(2)). This feature, common to many arbitration rules on interim measures, ensures the tribunal has the flexibility to craft effective, tailored orders that address the specific urgency and circumstances of the case. 

Setting the standard: when may parties obtain interim relief?

To obtain an interim measure, the applicant must show (i) that “harm not adequately reparable by an award of damages” will likely happen without it, and (ii) that this harm “substantially outweighs” any harm the other side might face if the measure were granted (Art 26(3)). The Draft Rules’ codification of these standards, which closely mirrors the language contained in Art 26(3)(a) of the United Nations Commission on International Trade Law (UNCITRAL) Rules, signifies a novel approach. Most arbitration rules contain no provision specifying the requirements for interim measures, including those of the International Chamber of Commerce (ICC), the Stockholm Chamber of Commerce (SCC), the Singapore International Arbitration Centre (SIAC), and the World Intellectual Property Organization (WIPO). A notable exception, other than the UNCITRAL Rules, are the arbitration rules of the Hong Kong International Arbitration Centre (HKIAC). However, the HKIAC rules only list the criteria as guidelines for the tribunal to consider rather than as requirements the parties must meet. The Draft Rules’ codification of explicit and binding requirements for interim measures enhances transparency and predictability for users, ensuring parties understand the threshold they must meet.

The Draft Rules are, moreover, unusual in that they set out only the aforementioned two requirements for granting an application for interim measures. In doing so, they omit a further, third requirement: namely, that an applicant must convince the tribunal that it has a “reasonable possibility” of succeeding on the merits of the claim. This omission is curious. The UNCITRAL Rules, which appear to have been used as guidance for the Draft Rules, clearly stipulate such a requirement in Art 26(3)(b). Moreover, the UPCA and the UPC Rules of Procedure (see Art 62(1),(4) and Rule 211(2),(3)) require the court to consider the chances of success on the merits (which will require a preliminary assessment of whether the patent is infringed) when deciding whether to grant a provisional measure. 

The reasoning behind the omission of the ‘merits’ hurdle in the Draft Rules is unclear. It is hardly imaginable in practice that a tribunal would issue an interim measure without considering whether the applicant has a possibility of succeeding on the merits. Yet the omission of this hurdle invites applicants to argue that they are not required to make out a prima facie case on the merits in order to be successful. The drafters of the Draft Rules may thus consider including this requirement in the final version or, at least, providing an explanation as to why it was omitted and whether tribunals are meant to take it into account when deciding applications for interim measures. Until this matter is clarified, this omission may give rise to some uncertainty on the part of the users.

Rare rule on ex parte interim decisions

In keeping with the drafters’ apparent objective of making interim measures more accessible, the Draft Rules expressly provide that they may be requested even on an ex parte basis when prior disclosure to the other side “risks frustrating the purpose of the measure” (Art 26(4)). This feature of the Draft Rules is likely meant to mirror Rule 212 of the UPC’s Rules of Procedure, which permits provisional measures without hearing the defending party, particularly where delay may cause “irreparable harm” or there is a “demonstrable risk” of evidence being destroyed.

The express ability for parties to obtain interim measures ex parte is rare: most major institutional rules, including those of the ICC, HKIAC, and London Court of International Arbitration (LCIA), do not expressly permit this. While the German Arbitration Institution (DIS) and Swiss Arbitration Centre’s International Arbitration Rules (ASA) do expressly allow ex parte applications, they restrict them to "exceptional circumstances"; a limitation absent from the Draft Rules. 

By expressly permitting ex parte applications, without additional restrictions, the Draft Rules have taken steps to encourage parties to make such applications and ultimately seem to encourage arbitrators to act swiftly in urgent cases. The Draft Rules thus provide an additional degree of speed and agility while entrusting tribunals with the responsibility of striking the appropriate balance between such agility and other procedural considerations.

Parties’ safeguards against ‘unjustified’ interim measures

As a safeguard against unjustified decisions on interim measures, the Draft Rules contain an express provision making an applicant liable for the other party’s costs if it is later determined that the measure should not have been granted (Art 26(10)). The relevant provisions do not, however, state that the applicant is also liable for damages (as is the case, for instance, in Art 26(8) of the UNCITRAL Rules or in Rule 213(2) UPC Rules of Procedure). The deliberate mention of costs and omission of damages suggests an intentional choice to limit liability to costs alone. This is surprising, because a successful interim measure application that turns out to have been unjustified may well cause substantial harm to the respondent party.

Most arbitration rules are silent on this issue and therefore leave the potential liability for unjustified applications to either the law of the seat of arbitration (which may provide for strict liability for costs and damages, see Art 17 G UNCITRAL Model Law on International Commercial Arbitration), or the law on the merits (which may require proving fault). 

While the Draft Rules therefore go further than most other rules by explicitly addressing remedies for unjustified measures, their limitation to liability for costs alone is difficult to justify and carries practical risks. In particular, this limited liability under the Draft Rules would likely be interpreted as the parties' choice to displace other broader liability regimes. Users of the PMAC Rules are therefore likely to welcome some additional guidance on the matter.

Our assessment: familiar foundations, distinctive departures

The Draft Rules adopt many established international standards but also introduce several notable departures. Most strikingly, the Draft Rules codify a defined two-limb test for interim measures yet omit the commonly used ‘likelihood of success on the merits’ criterion. They also stand out for explicitly permitting parties to apply for interim measures on an ex parte basis, as well as for limiting recovery in cases of unjustified interim measures to mere costs, risking the exclusion of liability for damages. These may well be deliberate policy choices, but their rationale should be clearly articulated to avoid any misunderstanding by future Draft Rules users.

Note: All references to rules refer to the versions of the rules in force at the time of publication.