Japan: Domestic Sonderhoff & Einsel Law and Patent Office

Sonderhoff & Einsel Law and Patent Office’s international team of professionals has provided services to international and domestic clients since its founding in Japan in 1910. As a full-service law firm, Sonderhoff & Einsel can provide expert legal advice on a wide spectrum of legal matters and is the adviser of many companies doing business in Japan.

Today, the firm employs 30 patent attorneys and nine attorneys (including Japanese, US, German and Chinese-qualified legal professionals), supported by a team of technical specialists, experienced translators and paralegals. The firm is jointly led by patent attorney Felix-Reinhard Einsel, managing partner and the only European to be licensed as a patent attorney in Japan, and Keiji Isaji, an attorney at law with more than 30 years’ experience in litigation, finance and regulatory affairs.

Recognising the importance of China for clients, the firm works in close collaboration with Sonderhoff & Einsel (Beijing) Patent Agency Office, founded in 2012.

Focus areas

The firm’s practice has an emphasis on all aspects of IP law – including patents, utility models, trademarks and designs, as well as unfair competition. Expert assistance is provided for counselling, prosecution, litigation, dispute resolution and licensing transactions.


Founded in Japan in 1910, Sonderhoff & Einsel Law and Patent Office has operated for more than 100 years as a leading firm with strong European ties. Its German founder, Karl Vogt, started his career in Japan at the German embassy; soon after being admitted as a Japanese patent attorney in 1910, he set up his patent and legal practice together with English and Australian co-founders. The following generations developed the firm into a recognised full-service law firm and a trusted partner of traditionally European, particularly German, companies with operations in Japan.

Practice areas

The reliable prosecution of patents has long been a core competence of the firm, covering a wide range of technologies, including mechanical and electrical engineering, materials science, chemistry and biochemistry and pharmaceuticals. For applicants from outside Japan, high-quality Japanese translations of patent applications are provided from German, English and Chinese, among other languages.

In trademarks, the firm’s specialist patent attorneys provide insightful advice on strategies and particularities for applications in Japan. Patent attorneys specialising in designs can advise and support clients throughout the whole design registration process – from registered design searches to filing and monitoring of rights after registration.

In its IP enforcement practice, Sonderhoff & Einsel’s counsel have developed a distinctive, cost-effective anti-counterfeiting practice that makes it one of the leading firms in Japan. Certain patent cases handled by Sonderhoff & Einsel have become cornerstone cases in the field.

The firm is also well versed in global transactions, with experience in a wide range of practice areas, including general corporate and commercial transactions, mergers and acquisitions, labour and employment, finance, aviation and dispute resolution.

Main address

Shin Marunouchi Centre Building
18th/19th Floor
1-6-2 Marunouchi
Tokyo 100-0005

Contact details

E: info@se1910.com
T: +81 3 5220 6500
F: +81 3 5220 6556
W: www.se1910.com

Other offices



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Issue 82