Clemens Ziegler

Dr. Clemens E. Ziegler, LL.M. (Georgetown Univ.)
Founding Partner

+32 495 79 48 35

Recognised by Who’s Who Legal in 2018, 2019, 2020, 2021 and 2022 as a “future leader” in competition.

Clemens is committed to help businesses to quickly adapt to new requirements, to realise cost savings and other efficiencies. He provides business-oriented and pragmatic advice on minimising antitrust risk and on EU State aid law. 

After over a decade in two major international law firms (Cleary Gottlieb and Hogan Lovells) in Brussels, with placements in Washington D.C. and Copenhagen, in 2019, Clemens started up his own boutique law firm in Brussels.

Advice in EU State aid law matters is a focus of Clemens’ practice. Further, not least due to his experience in competition compliance officer positions, Clemens also assists companies in managing antitrust risk, for instance by designing and implementing compliance programmes. He also advices on cooperation agreements and vertical agreements, including such with sustainability objectives. Clemens handles complex, multi-jurisdictional merger transactions and other types of regulatory filings. He also assists clients facing cartel investigations. More information on Clemens’ experience and the practice areas he covers can be accessed through the buttons below.

Clemens has particular experience in the maritime and energy industries, as well as in the automotive and telecommunications sectors. He has also worked in the area of pharmaceuticals and medical devices, in a number of industrial manufacturing sectors and areas of digitalised services.

Clemens regularly speaks and publishes on current developments in the areas of EU competition and State aid law. His native language is German; he is fluent in English, Italian and French and has a basic knowledge of Spanish and Dutch.

Clemens Ziegler at Ziegler State Aid Antitrust has built up an impressive competition law practice, described by respondents as an ‘incredibly good state aid expert.’
Who’s Who Legal, Future Leaders Competition Europe Research 2022

Sources report that Clemens Ziegler has ‘great expertise in energy law, and particularly in state aid law.’ He is described as ‘diligent, dedicated and responsive, and possessing great integrity’, while remaining ‘calm under pressure’. He also brings ‘notable experience in German competition law matters.’
Who’s Who Legal, Future Leaders Competition Europe Research 2019

Publications / Speaking engagements

One Time, Last Time, Or Why the Commission’s Approval of the Romanian CE Oltenia Lignite Restructuring Aid Approval Makes For an Accident, Not a Precedent. Annotation on Commission Decision of 26.1.2022 on the State Aid SA.59974 – 2021/C (ex 2020/N, ex 2020/PN) which Romania Partially Implemented for Complexul Energetic Oltenia SA
(2022) 21(2) European State Aid Law Quarterly 181 ff.

Energy transition – the Commission’s State aid decisions on the Dutch and German coal phase-out laws,
podcast series recorded for the  Energy Union Law series of the Florence School of Regulation (“FSR“), June and July 2021 (together with Cecilia Borelli — Episode 1 (Dutch coal exit), Episode 2 (German hard coal tender mechanism) and Episode 3 (Formal investigation procedure into German lignite compensations)

Administrative Procedure, chapter contributed to Leigh Hancher, Francesco Maria Salerno & Yvo de Vries (eds.), EU State Aids, 6th edition, April 2021 (co-authored with Paul-John Loewenthal)

COVID – 19 Temporary State Aid Framework, podcast recorded for the Energy Union Law series of the Florence School of Regulation, April 2020

Participating in panel titled Capacity mechanisms under scrutiny at the Energy Community’s conference on Competition Law in the Energy Sector, Vienna, December 2018

Participating in panel titled State Aid Hot Topics in FSR’s workshop on Competition Law and the Energy Sector, Brussels, October 2018

Speaking at 100th Lunch-Talk of GCLC – Global Competition Law Centre, Brussels, in a Panel on Antitrust and merger control law in times of Brexit, Brussels, May 2018

The Treaty State Aid Framework – Friend or Foe in the Energy Transition? (online lecture in FSR’s summer programme, titled Unpacking the Legal Content of the Clean Energy Package, May 2018)

What are the Consequences of Brexit on Competition Law and Policy Enforcement? at FSR workshop The Impact of Brexit on the UK and European Energy Markets, London, April 2018

What is State Aid? and Germany, chapters contributed to Leigh Hancher, Adrien de Hautecloque, Francesco Maria Salerno, State Aid and the Energy Sector, February 2018 (together with Dr Falk Schöning)

The British Aggregates saga – Looking back at an earlier stage of the selectivity discussion, chapters contributed to Caroline Buts, José Luis Bendía Sierra (eds), Milestones in State Aid Case Law. EStAL’s First 15 Years in Perspective, December 2017, as well as for the second Milestones edition, EStAL’s First 20 Years in Perspective 2022

Earlier publications / Speaking engagements

New issues in EU Security of Gas Supply
Moderating a Session at the Florence School of Regulation’s EU Energy Law and Policy Workshop, Berlin, February 2016​

The European Commission’s Extension of the Liner Shipping Consortia Block Exemption Regulation until April 2020, Journal of European Competition Law & Practice (JECLAP) 2014 (together with Matthew Levitt)

Getting the Deal Through When Time is of the Essence
Antitrust Strategies for Time Sensitive Transactions
, in: ABA, Section of Antitrust Law, The Threshold, Newsletter Of The Mergers & Acquisitions Committee, Spring 2010 (together with Gregory M. Sergi)

Humanitarian Intervention and Pretexts for War
A Critique of Ryan Goodman
, 100 Am. J. Int’l L. 107 (2006), in: 5 Hanse Law Review, No. 2 (December 2009), 175 ff. — abstract available here, full text available here.

Kosovo-Krieg der Nato 1999 und Irak-Krieg 2003
Völkerrechtliche Untersuchung zum universellen Gewaltverbot und seinen Ausnahmen
, published in Schriften zum Staats- und Völkerrecht, 2009
Title in English: “NATO’s Kosovo War 1999 and Iraq War 2003. Analysis in Public International Law Regarding the Prohibition on the Use of Force and its Exceptions”

Awards and recognitions

2022, 2021, 2020, 2019 and 2018

“Future leader”, Competition – Who’s Who Legal


“Foreign expert” for Germany in Competition Law – Chambers Global


“Recommended lawyer” for Competition Law – Legal 500 Belgium


Dr. jur., Philipps-Universität Marburg, 2009
LL.M., Georgetown University Law Center, 2009
Second State Exam in Law, Rhineland-Palatinate, 2005
First State Exam in Law, Julius-Maximilians-Universität Würzburg, 2003
Secondary Studies in European Law, Julius-Maximilians-Universität Würzburg, 2003


Bar of Frankfurt a.M., Germany
New York State Bar, USA
Brussels Bar (E-List), Belgium
Studienvereinigung Kartellrecht e.V. (Antitrust Lawyers Association)
European Maritime Law Organisation (EMLO)
Mehr Demokratie e.V. (Association for Direct Democracy)


Dr. Clemens Ziegler | Ziegler State Aid AntiTrust SRL