New acceleration mechanism for EPO oppositions
EPO may issue opposition decisions within 8 months where there are co-pending national or UPC proceedings

The EPO has issued detailed guidance on the accelerated timing of EPO oppositions in cases where the EPO is informed by the UPC or a national court of a contracting EPC member state that an infringement action or a revocation action relating to a European or unitary patent has been brought before it. The guidance follows the announcement of this initiative in late 2023. The new timeline is meant to shorten significantly the length of the opposition procedure. These acceleration measures apply with immediate effect and will also be applied to pending proceedings. What acceleration measures are adopted will depend on when the EPO is notified of parallel court proceedings.

The UPC and national courts usually inform the EPO that there is an infringement or a revocation action pending, and opposition proceedings should therefore be accelerated without a request from the parties. However, parties to the parallel opposition proceedings also may request accelerated processing of the opposition at any time.

The timelines below compare the timings in a standard opposition versus an accelerated opposition and the differences are summarised in the table. We also discuss acceleration of EPO appeals and how the accelerated opposition timeline fits in with the timeframe of the UPC proceedings.

Standard timeline for an opposition


Accelerated timeline for an opposition under new guidance


Comparison of time periods in a standard vs accelerated opposition

Time periodStandard opposition timelineAccelerated opposition timeline
Deadline for filing an opposition9 months from grant9 months from grant
Deadline for proprietor to reply to the opposition(s)4 months from the issuance of the invitation to reply.

Extensions may be requested and are granted if suitable reasons are provided.
3 months if the EPO is informed about the parallel proceedings before the opposition deadline.

Extensions are essentially not available unless there are exceptional, duly substantiated circumstances.
Issuance of a summons to oral proceedings (usually accompanied by the preliminary opinion)Usually ~4-6 months after the proprietor’s reply is filed but can be longer.Within 2 months of receipt of the proprietor’s reply if the EPO is informed about the parallel proceedings before the opposition deadline or before the proprietor’s reply is filed.


Within 2 months after the notification of parallel proceedings if the EPO is informed after the proprietor’s reply is filed.
Oral proceedings (date set by the summons)Usually ~7-10 months after the issuance of the summons, but can be longer.

The deadline for the last written submissions is usually 2 months before the oral proceedings.
Parties summoned to oral proceedings at minimum notice (2 months unless parties agree to a shorter period) if the EPO is notified regarding parallel proceedings before a summons is issued.

Last written submissions will also be due at some point before a hearing; there is currently no guidance on the timing of this.


Oral proceedings rescheduled to the earliest possible date (provided that the time saving is significant) if the EPO is notified of parallel proceedings after a summons has already been issued.

Written decisionUsually ~1-3 months after the oral proceedings.Within 1 month

In a standard opposition, it takes usually between 15 and 20 months from the opposition deadline to obtain a decision at the end of the hearing (or 16-23 months for a written decision). Opposition proceedings can take even longer, for example, if the case is complex or if there are multiple opponents. By contrast, with the new accelerated timeline, it may be possible to get a written decision from the opposition division as quickly as within 8 months from the opposition deadline if the EPO is notified of parallel proceedings during the 9-month opposition period.

The Carpmaels & Ransford team is now seeing this new guidance being applied in practice. For example, we have observed the EPO setting a 3-month period for the proprietor to respond to the opposition in instances where acceleration was requested before the expiry of the opposition period. We have also seen a summons and a preliminary opinion being issued within 2 months of the proprietor’s reply, and oral proceedings being scheduled for around 3 months from the issuance of the summons.

What about acceleration of appeals?

The accelerated timeline applies to EPO opposition proceedings. However, a first instance decision from an opposition division is often not the end of the story, and many cases are then appealed to the EPO Boards of Appeal. Acceleration of appeals is indeed possible on request by a party or a court in an EPC contracting state. Nevertheless, an appeal will of course lengthen the time it takes to reach a final decision at the EPO.

How does this fit in with the UPC timeframe?

The UPC aims to conclude its first instance proceedings within about a year from the start of an action, and this timeframe may be one of the main forces driving the new accelerated opposition timeline put forward by the EPO. To promote harmonised application of law and reduce the risk of inconsistency between decisions of the UPC and the EPO, it may in some cases be desirable to avoid running EPO opposition proceedings and a UPC action at the same time. It is with those situations in mind that the UPC Rules of Procedure incorporate provisions allowing the UPC to stay its own proceedings pending the outcome of opposition or limitation proceedings (including appeals) before the EPO in cases where a decision in those proceedings may be expected to be given rapidly.

However, in practice the UPC has so far been reluctant to stay its proceedings in view of parallel EPO oppositions. In two cases in which this issue was already considered, the request for a stay of UPC proceedings was rejected.

For example, in the case UPC_CFI_80/2023 (order ORD_579547/2023), the court held that in order to stay proceedings “there should be a concrete expectation (i.e. a known date in time) for a decision” and this date should be “in the near future” such that a decision at the EPO is clearly expected to be delivered before a decision by the UPC. Interestingly, in this case, the oral proceedings before the opposition division were only 3.5 months away at the point the request for a stay was rejected. The court considered that a rapid EPO decision required for the UPC to stay its own proceedings need not be the final decision (i.e. stay could be granted pending a first instance decision). Nevertheless, the court thought it likely that in this case the decision of the EPO’s opposition division will be appealed by at least one of the parties, and that the appeal would take some considerable time such that the final decision would not be expected for several years. It is unclear what circumstances would lead a UPC Division to consider that an opposition division decision was unlikely to be appealed, considering that in all cases the patent will be sufficiently commercially relevant for a UPC action to have been filed.

In another case, UPC_CFI_263/2023 (order ORD_591040/2023), the Court likewise considered that there was no “concrete expectation” of a decision from the EPO in the near future. The decision rejecting the request for a stay in this case was given before the issuance of a summons by the OD – in other words, some time before the opposition proceedings could be concluded.

UPDATE 1ST JUNE 2024: These decisions came out before the new timeline for accelerated EPO oppositions which considerably shortens the opposition procedure. However, on 28th May 2024, the UPC Court of Appeal confirmed in an order in Carrier Corporaton v BITZER Electronics A/S that as a general principle the UPC will not stay proceedings, and the mere fact that EPO proceedings are pending and indeed acceleration does not justify an exception. It highlighted the requirement in the UPC’s rules that a decision in the EPO must be expected to be given rapidly. The Court of Appeal acknowledged that this increases the chances of the UPC and the EPO reaching conflicting decisions, but indicated that the latter deciding body can take the earlier decision into account.

The timeline of the EPO opposition proceedings is constrained by the 9-month opposition period between the grant of the patent and the opposition deadline, which is specified in the EPC and cannot be reduced without needing to re-write the EPC. This effectively means that the EPO will not start the opposition procedure until after the expiry of the 9-month opposition period.

Thus, even with the new accelerated timeline, first instance EPO opposition proceedings cannot be as quick as a UPC action which may be started as soon as the patent grants and is supposed to be concluded within a year of the start.

Nevertheless, oppositions at the EPO will remain an important way to challenge validity of patents. This is not least because the UPC presently covers only 17 of the 39 contracting states of the EPC and cannot cover countries outside of the 27 EU member states.


The new accelerated EPO opposition timeline significantly reduces the length of the first instance opposition procedure and will no doubt help to provide legal certainty for the parties involved on a much shorter timescale, improve procedural efficiency of the proceedings and promote harmonisation in the application of law. It remains to be seen whether or not the new timeline will encourage the UPC to stay proceedings.