Simmons & Simmons, Linklaters and Herbert Smith Freehills (HSF) are among 20 law firms supporting an investigation into the legality of the UK retaining membership of the Unified Patent Court (UPC) after the UK leaves the European Union (EU).

The legal opinion, published just over a week ago, states that it is possible for a non-EU member state to remain legally part of the UPC, provided that the UK is bound by EU law in the jurisdiction of the UPC.

The opinion was delivered by Richard Gordon QC of Brick Court Chambers, a specialist in constitutional and EU law, and his fellow Brick Court barrister Tom Pascoe.

Gordon and Pascoe were instructed and funded by industry bodies the IP Federation and the Chartered Institute of Patent Attorneys, as well as an informal consortium of 20 law firms set up by Simmons intellectual property (IP) head Rowan Freeland.

Other consortium members include CMS UK, Gowling WLG, Bird & Bird, Collyer Bristow, Browne Jacobson and European IP firms Carpmaels & Ransford and EIP.

Freeland said: "It was my idea. I chose the counsel and wrote the instructions and got people's comments. We sent the instructions to barristers in late July and they came up with their opinion a week and a bit ago."

Simmons IP partner Kevin Mooney was also involved in getting the group together.

Freeland continued: "The perception was that the UPC agreement is technically not an EU agreement; it is an agreement between member states. Our question was: if we're not a member state, can we be part of it? And if we can be, should we be?

"The interesting thing about this opinion is that it suggests you can have a relationship with the EU that is confined to the jurisdiction of the UPC."

Linklaters IP partner Nigel Jones commented:  "It's a very interesting point and this clarification from counsel is very helpful in thinking through what the options are. There are hundreds of issues post-Brexit, which are viewed by relevant industry sectors and legal practice areas as critical – this is one of them."

Allen & Overy London IP litigation head Nicola Dagg added: "Richard Gordon QC's opinion analyses, in detail, the potential legal routes forward on the UPC. But the all-important issue is whether, in light of the UK's vote to leave the EU, there is any political will for the UK to be part of the UPC going forward, given that it would inevitably involve ceding a portion of sovereignty to the Court of Justice of the European Union.

"We tested support for the UPC with potential users of the court in a survey this June. Before the Brexit referendum, patent-heavy businesses believed the system would benefit their companies. However, at that point – with the spectre of Brexit looming – almost half said the UK's exit would make them rethink the proportion of patents they would opt out of the UPC system. The key question is what these potential users are thinking and planning now."