Mark Chacksfield KC

• Experience

  Patents & SPCs

  • Cabo Ltd v MGA Entertainment: this was a very substantial case concerning allegations of the infringement of competition law, and unjustified patent threats, as well as issues in passing off, which ran for six weeks in Court. The core of the allegation was that MGA, a titan of the toy industry, took steps to crush the launch of a new product by the Claimant start-up, using threats of (inter alia) patent infringement and threats to withdraw its blockbuster LoL Surprise! toy to coerce retailers to agree not to take Cabo’s competitive product.  As a result Cabo’s toy launch failed, and substantial damages were claimed.  Judgment is awaited.
  • Emotional Perception AI Ltd v Comptroller-General of Patents [2024] EWCA Civ 825, [2025] 1 All ER 790, [2024] RPC 25: in this highly anticipated appeal from the decision below, the Court considered the construction of the phrase ‘program for a computer’ under the exclusions to patentability in the Patents Act. The Court overturned the decision of Mann J, and held that an AI (particularly an ANN) was within the exclusions, and so rejected the application.  The case is now under appeal to the Supreme Court, to be heard in July 2025.
  • InterDigital Technology Corp v Lenovo Group Ltd [2024] EWCA Civ 743, [2024] RPC 24: this was the appeal from the below two decisions, and in particular focussed on the widely important arguments as to whether a Court-determined FRAND licence was limited to recovering royalites only back as far as six years, and the payment of interest on such delayed royalties.  The Court affirmed the decisions below, and established these important principles as a matter of FRAND law. In addition the Court accepted InterDigital’s arguments that the original decision had set too low a lump sum, increasing the total payable by Lenovo to $178 million.
  • Lenovo Group Ltd v. InterDigital Technology Corp [2024] EWHC 596 (Ch), [2024] RPC 18: this was the first case in which the Court was faced with an application by an implementer of a telecommunications standard for a so-called ‘interim licence’ pending the final determination of FRAND licence terms by the English Courts. The Court rejected Lenovo’s application and set out a number of basic principles. Indeed this to date remains the only claim for an interim injunction in which the implementer has succeeded in its defence.
  • Emotional Perception AI Ltd v Comptroller-General of Patents: [2023] EWHC 2948 (Ch), [2024] Bus LR 14, [2024] RPC 2: one of the highest profile cases in the field of AI in recent years, this case concerned the question of whether and to what extent AI (more specifically) ANNs were excluded from patentability as ‘programs for a computer’.  In a hugely widely commented upon decision, the Judge accepted the applicant’s argument that an ANN was not (nor contained) a computer program, and accordingly held the application to be allowable.
  • InterDigital Technology Corp v Lenovo Group Ltd [2023] EWHC 1578 (Pat), [2023] R.P.C. 14: following on from the below decision, this judgment concerned in particular the question of interest on royalties on past sales, establishing for the first time that interest should be paid on those royalties, on the facts of this case at 4% compounded, amounting to an extra $46 million.
  • InterDigital Technology Corp v Lenovo Group Ltd [2023] EWHC 539 (Pat),[2023] EWHC 1583 (Pat), [2023] RPC 13: this very high profile judgment was the UK’s second ever FRAND rate-setting dispute, and one of only a handful world-wide, which involved both fact evidence and with, between them, the parties calling 14 separate expert witnesses on issues as diverse as valuation, foreign law, patent counting and hedonic regression analysis.  The trial ran for 5 weeks, and traversed a wide range of legal issues argued to be left open out of the FRAND judgment in Unwired Planet and the post-trial injunction decision in Apple v Optis, and has been widely reported in the legal and technical literature since.
  • Kigen (UK) Ltd v Thales DIS France SA [2022] EWHC 2846 (Pat), [2022] 11 WLUK 98: This was a jurisdictionally important case which addressed the question of when and in what circumstances an implementer of a telecommunications standard may bring a claim before the English Courts seeking the determination of the terms of a FRAND licence from a holder of standards essential patents.  Whilst jurisdiction was established in principle, the Court stayed the action unless and until the implementer gave unequivocal undertakings to take the FRAND licence on the terms settled by the Court (if offered by the implementer).
  • InterDigital Technology Corp v Lenovo Group Ltd: this was the fourth technical trial between InterDigital and Lenovo in their wide ranging FRAND dispute.  The case focussed on carrier aggregation and engaged a wide ranging and in-depth analysis of the approaches taken to similar technologies in other standards, as well as considering novel arguments about the ‘collocation’ basis for alleging obviousness.
  • InterDigital Technology Corp v Lenovo Group Ltd [2022] EWHC 10 (Pat),[2022] 1 WLUK 3: this decision was the second technical trial between InterDigital and Lenovo.  The argument concerned E-TFC selection in HSUPA, and involved a technically complex analysis of the history and nature of the evolving standards at the relevant point in time.
  • Optis Cellular Technology LLC v Apple Retail [2021] EWCA Civ 1619, [2021] 11 WLUK 94: This was the appeal from one of the technical trials in the high profile Optis v Apple FRAND litigation, traversing questions of construction, obviousness, the evidential burden on infringement and with a particular focus in argument on the scope and extent of the so called ‘AgrEvo obviousness’ argument in a telecommunications context.
  • Optis Cellular Technology LLC v Apple Retail [2021] EWHC 1739 (Pat), [2022] RPC 6: This was a further successful patent validity and  infringement claim brought against Apple in Optis’ ongoing litigation. In particular Mark ran and defended against the potentially enormously important novel ‘estoppel’ defence advanced by Apple, to the effect that the alleged ‘late’ declaration by Optis’ forerunner in title barred Optis from enforcing its patent rights in the UK.
  • Vestel Elektronik v Access Advance LLC [2020] EWCA Civ 440, [2021] 4 W.L.R. 60, [2021] F.S.R. 28: this jurisdictional appeal involved a novel attempt by an implementer of the HEVC/H.265 standard to bring a claim for a FRAND declaration against the administrator of a patent pool and a patentee therewithin.
  • Optis Cellular Technology LLC v Apple Retail [2020] EWHC 2746: a successful patent validity and infringement claim brought against Apple, and potentially opening the door to a FRAND determination in a claim publicly valued by Apple as being worth up to US$8 billion.
  • Pfizer v F Hoffmann-La Roche AG [2019] EWHC 1520, [2019] RPC 14: this case remains unique as the first successful defence by a patentee of an ‘Arrow’ declaration. Involving extensive questions of the law of declaratory relief and also of Belgian practice and procedure, the Court for the first time held that no declaration should be granted, and therefore refused to opine on the underlying technical issues.
  • Actavis Group PTC EFH v ICOS Corp [2019] UKSC 15, [2020] 1 ALL E.R. 213, [2019] RPC 9: the leading Supreme Court decision considering the correct approach to obviousness in UK law.
  • Eli Lilly v Genentech [2019] EWHC 387, [2019] WLUK 15: described by Arnold J as one of the most complex patent cases he had ever tried, this biopharmaceutical infringement/validity action involved 24 reports from 9 experts running to close to 700 pages.  Its focus was on the treatment of rheumatoid arthritis and psoriasis using inhibitory antibodies to the interleukin IL-17A/F, and infringement by Lilly’s ixekizumab MAb product.  See also the parallel SPC decision [2019] EWHC 388, [2019] 3 WLUK 4.
  • Technetix v Teleste [2019] EWHC 126 (IPEC), [2019] F.S.R. 19: an IPEC validity and infringement action notable for both being the first attempt to introduce into the UK a Formstein/ensnarement defence to infringement by equivalents, and also for being a case in which Mark’s client, the Defendant, was successful having chosen not to call their own evidence in the light of the cross examination of the Claimant’s expert.
  • Chugai Pharmaceutical Co Ltd v UCB Pharma SA [2018] EWHC 2264 (Pat), [2018] 8 WLUK 232: a claim for substantial royalties under a biopharmaceutical patent licence, the resolution of which required the defence of an infringement claim of a US patent run under US patent law.
  • Fujifilm Kyowa Kirin Biologics Co Ltd v AbbVie Biotechnology [2017] EWHC 395 (Pat): the first ‘Arrow declaration’ case to have come to trial, paving the way for the subsequent explosion in interest in this novel form of relief; Mark having also appeared for Arrow in the original case. See also the related decisions: [2017] EWCA Civ 1, [2017] RPC 9; [2016] EWHC 3383, [2017] RPC 8; [2016] EWHC 2204, [2017] RPC 7.
  • Unwired Planet International Ltd v Huawei Technologies Co Ltd [2017] EWCA Civ 266:  the first of the Unwired Planet cases to come to appeal, and was the subject of intense attention from the industry. Having succeeded at first instance, Unwired Planet successfully defended the judgment on appeal, paving the way for the much discussed FRAND action.

  Jurisdiction & Remedies

  • Kigen (UK) Ltd v. Thales DIS France SA [2022] EWHC 2846 (Pat), [2022] 11 WLUK 98: This was a jurisdictionally important case which addressed the question of when and in what circumstances an implementer of a telecommunications standard may bring a claim before the English Courts seeking the determination of the terms of a FRAND licence from a holder of standards essential patents.  Whilst jurisdiction was established in principle, the Court stayed the action unless and until the implementer gave unequivocal undertakings to take the FRAND licence on the terms settled by the Court (if offered by the implementer).
  • Vestel Elektronik v Access Advance LLC [2020] EWCA Civ 440, [2021] 4 W.L.R. 60 [2021] F.S.R. 28: this jurisdictional appeal involved a novel attempt by an implementer of the HEVC/H.265 standard to bring a claim for a FRAND declaration against the administrator of a patent pool and a patentee therewithin.
  • Chugai Pharmaceutical Co Ltd v UCB Pharma SA [2017] EWHC 1216 (Pat): this was an application to strike out a claim for want of subject matter jurisdiction which concerned the limits of the power of the Court to consider matters said to engage the validity of foreign patent rights.
  • Fujifilm Kyowa Kirin Biologics Co Ltd v Abbvie Biotechnology [2017] EWCA Civ 1: This was an appeal from the first instance decisions of Henry Carr J (on subject matter jurisdiction) and Arnold J (on personal jurisdiction) in litigation concerning the availability and scope of ‘Arrow declarations’ relating to the world’s largest pharmaceutical product, Humira.
• Education & awards
  • BA in Natural Sciences, Zoology (double 1st), Clare College, Cambridge 1997; Hurst Prize for Zoology.
• Professional memberships
  • Chancery Bar Association
  • Intellectual Property Bar Association
• Irish Qualifications

  Mark has been called to the Irish Bar, but is not presently on the Roll of Practising Barristers; straightforward administrative steps would need to be taken before he can accept instructions as an Irish barrister.  Please contact one of the clerks to discuss how we may assist on European work.

• Hobbies & interests

  In an earlier life Mark was a keen sportsman, fencing at a national level, coming 2nd as an U20 epeeist, and once squeaking into the top 8 in the national championships. He was also a committed modern pentathlete, obtaining his Blue at Cambridge. Now, however, his exercise is mostly limited to carrying boxes of papers, an occasional run home from chambers and kicking a ball around with his three much loved children. He also remains involved in modern pentathlon, through a charity set up by Mark and two of his team mates (now with 200 supporters). He is a board member of the ENT UK Foundation, the philanthropic and fundraising arm of ENT UK, and a trustee of the Berkshire, Buckinghamshire and Oxfordshire Wildlife Trust, part of the national network of Wildlife Trusts and which employs 150 staff, looking after 85 nature reserves and four educational centres supported by 1,700 active volunteers.  As a biologist by training, Mark has had a lifelong interest in wildlife and the environment, and is trying to learn something about regenerative land use and rewilding. He also loves travel (with a limited carbon footprint), good food and music (mostly of the type with irritating repetitive beeps).

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