Kei Matsumoto

Kei Matsumoto

Baker & McKenzie (Gaikokuho Joint Enterprise)


Kei Matsumoto is a member of the Firm's IP Tech group in Tokyo. Prior to joining Baker McKenzie, he worked in the patent litigation division of a major US law firm, where he handled patent litigation involving Japanese companies and other litigation in the US. Kei also has considerable experience in dispute resolution cases inside and outside the courts as well as corporate/M&A related cases. Kei is a native Japanese speaker and is fluent in English.

Practice Focus

Kei primarily handles intellectual property transactions and domestic and international patent disputes. He provides overall legal advice on the protection of intellectual property, contents of contracts and other related issues to Japanese companies establishing operations overseas as well as clients in IT industry. He also handles M&A related work and a variety of dispute resolution cases. Recently, Kei focuses on practices related to the Long-Term Care Insurance Act and other social security issues.

Representative Legal Matters

  • Researched the legal systems for protection of trade secrets in 7 countries including Japan and reported the results for "The commissioned project of industry and economy in 2014 (research and study regarding protection of trade secrets)" of the Ministry of Economy, Trade and Industry. 
  • Worked on patent litigation concerning optical discs and semiconductors in the US where Japanese companies were involved.
  • Represented a foreign company in patent infringement litigation and in an action against a patent invalidation trial.
  • Represented a client in negotiations with respect to an acquisition of a major hotel by conducting due diligence and drafting contracts.
  • Represented and advised a major US IT company (from Japan’s end) with respect to review of contract and its expansion in the Japanese market. 

Professional Associations and Memberships

  • New York State Bar Association - Member
  • Dai-ichi Tokyo Bar Association - Member
  • Japan Federation of Bar Associations - Member
  • American Bar Association - Member

Corporate Responsibility

Kei actively works for juvenile protection cases.


  • New York~United States (2007)
  • Japan (2001)


  • Northwestern University School of Law (LL.M.) (2006)
  • The University of Tokyo (LL.B.) (1999)


  • English
  • Japanese

Publications and Articles

  • Co-author, "Protecting IP Licenses and Jointly Owned IP in the Age of COVID-19: Insolvency and Force Majeure Events under Japanese Law," GRUR International, Volume 70, Issue 5, May 2021, Pages 463-485, German Association for the Protection of Intellectual Property and Copyright e.V., June 2021
  • Co-author, "Trade secret protection programs and practices in foreign countries: Discussing viable legal actions in the U.S., Korea, China, Taiwan and Germany," Business Law Journal, Lexis Nexis, May 2016, Language: Japanese
  • Author, "Technical information leakage prevention and countermeasures," Business Homu, Chuokeizai-Sha, September 2012
  • Co-author, "Cloud Computing and the Law," Kinzai, October 2011, Language: Japanese
  • Co-author, Business Law, Chuokeizai-sha, 2004, Language: Japanese
  • Chapter, "Amendment to the Labor Standard Law of Japan," Asian Legal Business, 2004, Language: English