Stephan Barthelmess’ practice focuses on German and European competition law, including administrative and civil litigation before the German and European courts.

He has published various articles in the field of antitrust law, and is a co-author of the Loewenheim commentary on European and German antitrust law (4th Edition, 2020).

Matters handled by Stephan in the area of merger control include the representation of EMC in merger control proceedings before the German Federal Cartel Office concerning the acquisition of a large patent portfolio of Novell by CPTN, a consortium of EMC, Microsoft, Apple, and Oracle; a major fossil fuel producer in merger control proceedings before the European Commission regarding the acquisition of full control over Wingas; construction materials company Xella in merger control proceedings before the Federal Cartel Office and the German courts concerning its proposed acquisition of the Danish company H+H; and The Coca-Cola Company with respect to the acquisition of the Apollinaris mineral water business.

Stephan also has substantial experience advising clients in cartel and other antitrust investigations, including the representation of U.S. chemicals company DuPont in a Commission investigation into alleged anti-competitive behavior in connection with a cooperation with Honeywell concerning the development and production of a new environmentally sustainable automotive air conditioning refrigerant; MediaSaturn Holding in the EU proceedings against Intel for abuse of a dominant position; and a European Commission investigation in the consumer electronics industry.

Litigation matters handled by Stephan include the representation of IMAX Corporation in various proceedings involving antitrust aspects against operators of IMAX movie theaters in Germany; KM Europa Metal AG in proceedings before the Higher Regional Court in Celle and its constitutional complaint against the service of U.S. class action complaints involving antitrust aspects; and mobile telecommunications company Huawei in a referral proceeding before the European Court of Justice relating to patent infringement litigation before the Düsseldorf Regional Court based on Standard Essential Patents.

Stephan joined the firm in 1986, became a partner in 1995 and became senior counsel in 2015. He has been resident in the New York, Brussels, Paris, and Frankfurt offices.


Germany,” The Dominance and Monopolies Review – Edition 7, 2019.

“The Concept of Agreements and Concerted Practices in the Context of Resale Price Maintenance: Make Fit What Doesn’t Fit?” Europäisches, deutsches und internationales Kartellrecht, Otto Schmidt, 2018.

Germany,” The Dominance and Monopolies Review – Edition 6, 2018.

“Germany” by Stephan Barthelmess and Tilman Kuhn, The Dominance and Monopolies Review, Law Business Research, August 2017, p. 160-175 (Chapter 11).

“Germany” by Stephan Barthelmess and Tilman Kuhn, The Dominance and Monopolies Review, Law Business Research, June 2014, p. 146-161 (Chapter 10). 

“Germany,” by Stephan Barthelmess and Tilman Kuhn, The Dominance and Monopolies Review, Law Business Research, June 2013.

“Procedural issues concerning injunction proceedings under German law regarding standard-essential patents”, by Stephan Barthelmess, Wirtschaft und Wettbewerb, February 2013.

Loewenheim (Hrsg.)/Meessen/Riesenkampff, Kartellrecht. Europäisches und Deutsches Recht. Kommentar, 2. Auflage 2009, C.H. Beck Verlag (coauthor).

EWS (Betriebsberater für Europarecht), Heft 4/2010, S. 117 - Die Intel Entscheidung der Europäischen Kommission: Der erste Test des „as-efficient-competitor“-Tests (The Intel decision of the European Commission: The first test of the „as-effecient-competitior“-test).

WuW, Heft 6/2010, S. 626: Die Lizenzierung standardessentieller Patente im Kontext branchenweit vereinbarter Standards unter dem Aspekt des Art. 101 AEUV (The licensing of standard-essential patents under the Aspect of Article 101 TFEU) (with Nicolaus Gauss).