Mark C. McLennan

Partner Intellectual Property

New York +1 212 909 3451

Mark C. McLennan

Overview

Mark McLennan is an intellectual property partner in the New York office of Kirkland & Ellis LLP. He leverages his technical background in pharmacology to advise clients in a range of industries, including pharmaceuticals, biotechnology and medical devices. Mark was recently recognized as a “Key Lawyer” in The Legal 500: Life Sciences 2025.

Mark’s extensive litigation experience spans pre-suit strategy through to bench and jury trials, including pretrial arguments and examination of fact and expert witnesses. He has also represented clients in inter partes reviews before the PTAB — acting for both Patent Owners and Petitioners — and in Section 337 investigations before the International Trade Commission. Beyond trial work, Mark counsels clients on IP-related contract disputes, patenting strategy and due diligence.

Mark brings an international perspective to his practice, drawing on experience in global litigation coordination, a secondment in Kirkland’s London office and several years practicing in Australia. 

Mark’s pro bono practice includes advocating for persons seeking asylum. He recently second chaired a two-week evidentiary hearing in a Texas capital case, securing commutation of his client’s death sentence to life imprisonment — an achievement honored with the Texas Defender Service’s 2024 Light of Justice Award. Mark is also involved in Kirkland’s inclusion efforts, serving on the leadership committee of the Firm’s Pride Affinity Group.

Recent Representative Matters

  • Representing Moderna in an appeal arising from a patent infringement suit in D. Del. brought by Arbutus Biopharma and Genevant Sciences relating to Moderna’s COVID-19 vaccine.
  • Representing Caterpillar at the ITC in an action against Bobcat relating to control systems in heavy machinery (Certain Heavy Machinery and Components Thereof; Inv. No. 337-TA-1507).
  • Represented Alcon in a patent infringement suit in N.D. Tex. brought by HOYA, relating to medical devices used in cataract surgeries; won summary judgment of no infringement on two of three patent families and of no willful infringement, after which the case settled shortly before trial.
  • Representing Boehringer Ingelheim in a patent infringement suit in D. Del. against 15 ANDA filers seeking approval to manufacture and sell generic versions of Boehringer’s Jardiance® (empagliflozin) products used to treat type II diabetes.
  • Represented Watson in several patent infringement suits brought by UCB Pharma in D. Del., relating to rotigotine transdermal delivery systems (Neupro®). Mark was part of the trial team for a 4-day hearing that resulted in the invalidation of a polymorph patent, and, in a follow-on proceeding, successfully invalidated the sole patent-in-suit.
  • Advised a publicly traded company on a multi-jurisdictional patent suit concerning consumer electronic devices, including a strategic “patent mining” review of their international patent portfolio.
  • Represented Abbott Cardiovascular, successfully defending against five inter partes review petitions filed by Edwards Lifesciences challenging Abbott’s patents covering MitraClip®, resulting in denial of institution for all five petitions.
  • Represented Pfizer in inter partes review proceedings before the USPTO challenging patents directed to methods of treating breast cancer with trastuzumab (Herceptin®), as well as methods of humanization and purification methods. Successfully. The Kirkland team successfully invalidated several patents before Pfizer obtained a favorable settlement.
  • Represented Teva in several district court proceedings (D.N.J.) against Celgene concerning the drug pomalidomide (Pomalyst®). Teva obtained favorable settlement during expert discovery after years of litigation.
  • Represented Teva in an ANDA case against Merck concerning the drug alvimopan (Entereg®). Teva obtained favorable settlement following expert discovery.

Herbert Smith Freehills, Melbourne, 2012–2015

More

Thought Leadership

Seminars 

Panelist, “Early Stage Patent Litigation Strategy: The First 90 Days,” Kisaco Pharma & Biotech Patent Litigation Summit, Boston, MA, September 2026

Panelist, “Patent Strategy Under Pressure: Adapting to the Inflation Reduction Act,” Kisaco Pharma & Biotech Patent Litigation Summit, Philadelphia, PA, November 2025

Panelist, “Legal, Regulatory, and Commercial Strategies for the Innovator and Biosimilars Marketplace,” 15th Summit on Biosimilars & Innovator Biologics, New York, NY, June 2024

Co-Chair and Panelist, “LGBTQ+ Rights & Representation at the Crossroads,” Outspoken East 2022 Leadership Conference, New York, NY, June 2022 

“Patent and Technology Best Practices for 2017,” Intellectual Property Institute Panel, Lavender Law Conference, San Francisco, CA, August 4, 2017

Recognition

Recognized as a “Key Lawyer” in The Legal 500: Life Sciences, 2025

Recipient of Light of Justice Award by the Texas Defender Service, 2024

Recipient of Kirkland & Ellis Pro Bono Service Award, 2017–2023

Selected as a New York “Rising Star" for Intellectual Property Litigation by Super Lawyers magazine, 2020–2022

Credentials

Admissions & Qualifications

  • 2017, New York
  • 2013, High Court of Australia
  • 2012, Victoria, Australia (inactive)
  • Registered to practice before the United States Patent and Trademark Office

Courts

  • United States District Court for the Southern District of New York
  • United States Court of Appeals for the Federal Circuit

Education

  • Columbia Law SchoolLL.M.2016
    Harlan Fiske Stone Scholar
  • Monash UniversityLL.B.First Class Honors2012
  • Monash UniversityB.S., Pharmacology2012