Expert witnesses in patent litigation around the world

Managing IP is part of Legal Benchmarking Limited, 1-2 Paris Gardens, London, SE1 8ND

Copyright © Legal Benchmarking Limited and its affiliated companies 2026

Accessibility | Terms of Use | Privacy Policy | Modern Slavery Statement

Expert witnesses in patent litigation around the world

geek.jpg

Expert witnesses can be decisive in the outcome of patent cases, but rules on their use vary widely. We invited correspondents in Germany, Japan, the UK and US to discuss procedures and practical tips

geek.jpg

With so much IP litigation today being international, and involving an element of forum-shopping, parties have to weigh up many considerations when deciding where and when to bring an action, or how to defend it.

Some of these questions are purely legal: What rights do we have? Do we have standing? What actions are permitted in a particular jurisdiction? But many questions are also strategic: How long will a case take? What will it cost? How will it be decided? What evidence can be brought? Often, these strategic questions are decisive for the outcome of the dispute.

In patent litigation in particular, the role played by expert witnesses can be vital, especially in cases where the technology is complex and judgements about validity and infringement can be finely balanced. And yet the rules on the use of experts vary greatly between different jurisdictions.

Germany, Japan, UK and US compared

In a special feature published this month, we invited correspondents in Germany, Japan, the UK and US to describe how expert witnesses are used in litigation in those four jurisdictions, and also how parties can make the most of expert witnesses.

In Germany, courts recognise both court-appointed experts and party experts – though in practice they are only used in a tiny number of cases. Courts place tight restrictions on the use of court-appointed experts, while party experts may be of limited value and may even do more harm than good.

Japan also has different types of experts, and the role of judicial research officials and technical advisers is especially important in patent cases. Technical advisers in particular are now an accepted and well understood part of litigation in the country.

In the UK courts, experts play a vital role and can even be instrumental in the outcome of a case. Selecting the right expert and carefully instructing them is therefore a crucial part of litigation strategy. What is required of experts has been elucidated in a number of cases over the years and it is also important to consider personality issues: how credible will your expert be before a judge, particularly in cross-examination?

Similarly, in US litigation both consulting and testifying experts provide the court with invaluable assistance that may be case determinative (and a strong expert report may lead to pre-trial settlement). The standards expected of experts have been clarified in federal rules and case law and, as in the UK, the ability to select and prepare your expert is a key skill for litigators.

Comments welcome

We selected these four countries as they are among the most important in patent litigation globally; we may cover other countries in future issues if readers are interested, so please do let us know via the comments.

more from across site and SHARED ros bottom lb

More from across our site

Lawyers at Carpmaels & Ransford explain how the healthcare sector has not simply participated in the UPC’s early years, but actively shaped it
The firm has hired former in-house counsel Quintin Cassady to lead the launch of the new office
The combined firm has strong IP credentials across the US, Middle East, UK and Europe, despite Taylor Wessing’s German and French practices not joining
Priya Nagpal, who this month became the firm’s eighth IP partner, says its cross-practice expertise in areas closely linked to IP was a key draw
Harm van der Heijden is to join Ankar as head of patent innovation after 17 years in private practice
Alabama attorney Miya Aladebumoye has launched a new firm built on ‘big law’ experience and a personal touch approach
A UKIPO campaign aimed at combating fakes in the pre-loved fashion market and registration of the first Portuguese craft and industrial geographical indication were also among the top talking points
Chris Adams, Managing IP’s research lead, joins us to explain what practitioners need to know ahead of our first rankings release of 2026
Another IP litigator joins Winston & Strawn in Dallas as firm seeks to keep pace with ‘rapid’ growth of Texas market
Anthony O'Malley will replace Andrew Blattman at IPH, which owns several large IP firms across Australia, Asia and Canada
Gift this article