Brick Court Chambers

Marie Demetriou QC

Marie Demetriou QC

YEAR OF CALL: 1995    YEAR OF SILK: 2012

“The quality of her oral submissions is fantastic”, “Excellent on her feet”
Chambers and Partners 2018

Marie Demetriou QC has a broad practice specialising in competition law, EU law, public law and human rights.  She is highly ranked in all of these areas by the legal directories and is regularly nominated for legal awards.  In 2018, Marie was shortlisted as the Lawyer’s Barrister of the Year and in 2016,Marie was awarded EU and Competition Law Silk of the Year by Legal 500, which in addition nominated her as Public Law Silk of the Year.  Marie was also one of three nominees for Chambers & Partners Competition Law Silk of the Year. In 2015, Marie was appointed Standing Counsel to the Competition and Markets Authority, a position she continues to hold, representing the CMA in its major litigation in the courts.Marie has been Chair of the Bar European Group between 2016-2018.

Marie Demetriou QC has a broad practice specialising in competition law, EU law, public law and human rights.  She is highly ranked in all of these areas by the legal directories and is regularly nominated for legal awards.  In 2018, Marie was shortlisted as the Lawyer’s Barrister of the Year and in 2016,Marie was awarded EU and Competition Law Silk of the Year by Legal 500, which in addition nominated her as Public Law Silk of the Year.  Marie was also one of three nominees for Chambers & Partners Competition Law Silk of the Year. In 2015, Marie was appointed Standing Counsel to the Competition and Markets Authority, a position she continues to hold, representing the CMA in its major litigation in the courts.Marie has been Chair of the Bar European Group between 2016-2018.

Marie’s current case-load includes acting for CMA in appeals in the CAT, acting for a variety of commercial clients in large-scale competition damages claims, as well as representing private clients, public bodies and NGOs in public law and EU-related litigation before both the English and European Courts.  Some current and recent highlights of Marie’s practice are:

  • Successfully acting for Monarch Airlines in the Court of Appeal in relation to the allocation of valuable landing slots after Monarch was placed into administration (R(Monarch Airlines Limited) v Airport Coordination Limited [2017] EWCA Civ 1892).
  • Acting for the CMA in Ping v CMA (judgment pending) on the lawfulness of bans on internet sales.
  • Representing Apple in its competition law/ FRAND claim against Qualcomm arising out of the licensing by Qualcomm of its chips used for Apple devices.
  • Acting for the Federal Deposit Insurance Corporation in a large LIBOR damages claim against several banks.
  • Representing the CMA in the ‘pay for delay’ litigation both before the CAT (GlaxoSmithKline v CMA [2018] CAT 4, in the reference made by the CAT to the CJEU, and intervening in the Lundbeck appeals in the CJEU
  • Successfully challenging the Government’s nationwide policy to deport EU nationals found sleeping rough (Gureckis and others v Secretary of State for the Home Department [2017] EWHC 3298 (Admin).
  • Representing Mr Micula in the High Court and Court of Appeal in his application to enforce his ICSID arbitration award in circumstances where the European Commission has determined that enforcement would amount to state aid (Micula v Romania).
  • Acting for the UK in Gibraltar’s first (and probably last) reference to the CJEU (Case C-267/16 Buhagiar v Ministry of Justice). 
READ MORE M
Expand All
  • Competition M

    Marie has been Standing Counsel to the Competition and Markets Authority since 2015.  She is instructed in many of the leading competition cases, both in the CAT and in the High Court.  As well as acting for the CMA in its litigation (including the ‘pay for delay’ appeals, Eurotunnel/SeaFrance in the Supreme Court and Ping v CMA), she has acted in a large number of competition damages claims (including those arising from the decisions in Trucks, FX, Gas Insulated SwitchgearPower CablesBall BearingsCathode Ray TubesMobile Phone Batteries) as well as in stand-alone competition actions and FRAND claims (Marie is currently acting for Apple in its claim against Qualcomm).  In 2016, Marie was awarded Competition Law Silk of the Year by Legal 500.  In 2017 Marie delivered the annual David Vaughan QC lecture on antitrust litigation.

    Notable cases include:

    • Société Coopérative de Production SeaFrance v CMA [2015] UKSC 75, successfully represented CMA in appeal against meger decision.
    • Ping v Competition and Markets Authority, CAT, lawfulness of internet sales ban.  Represented CMA.
    • GlaxoSmithKline v CMA (“pay for delay”) [2018] CAT 4, reference before CJEU pending.  Represented CMA.
    • Apple v Qualcomm (Article 102 / FRAND claim in relation to licensing by Qualcomm of its chipsets used in Apple devices; judgment on jurisdiction [2018] EWHC 1188 (Pat).  Representing Apple, instructed by Boies Schiller LLP.
    • Iiyama v Samsung and others [2018] EWCA Civ 220.  Acted for Philips, instructed by Slaughter and May.
    • Merricks v Mastercard, appeal pending.  Acting for UK consumers in collective action; instructed by Quinn Emanuel.
    • Sky/ Fox; acted for CMA in investigation into public interest in permitting Sky Fox merger.
    • Federal Deposit Insurance Corporation v Barclays Bank Plc (large competition damages claim arising out of LIBOR manipulation; acting for claimant, instructed by Quinn Emanuel.
    • Veolia and others v Fiat Chrysler and others (acting for claimants in relation to Trucks cartel, instructed by Hausfeld).
    • National Grid and Scottish Power v ABB and others; acting for NKT, instructed by Addleshaw Goddard in large cartel damages claims arising from the Power Cables Cartel.
    • Vattenfall v ABB and others; acting for NKT, instructed by Addleshaw Goddard; further claim arising from Power Cables Cartel.
    • International Exchange Inc v Competition and Markets Authority [2017] CAT 6; successfully represented CMA in ICE’s appeal against CMA decision requiring unwinding of merger.
    • Microsoft v Sony, Samsung and LG Chem [2017] EWHC 374 (Ch); acted for LG Chem, instructed by Steptoe and Johnson; successfully challenged the jurisdiction of the English court to determine this large cartel damages claim.
    • CMA market investigation into retail banking; acted for CMA.
    • CMA market investigation into energy; acted for CMA.
    • Deutsche Bahn v Morgan Crucible [2014] UKSC 24; (successfully persuaded Supreme Court to strike out claim against Morgan crucible on the ground it was time barred; instructed by Clifford Chance).
    • National Grid v ABB and others [2009] EWHC 1326 (Ch), (cartel damages claim arising from Commission decision in gas-insulated switchgear
    • Cooper Tyre and Rubber Co v Bayer and others (Commercial Court; cartel damages claim)
    • Air Cargo, acting for SAS
    • Crest Nicholson Plc v OFT [2011] CAT 10 (appeal against penalty; bid-rigging in construction industry)
    • BSkyB v Competition Commission; Virgin Media v Competition Commission [2010] EWCA Civ 2 (Court of Appeal; application of media plurality provisions in Enterprise Act; Sky's acquisition of shareholding in ITV)
    • Sky v Ofcom; FA Premier League v Ofcom (CAT; Pay TV; challenge to Ofcom's decision to require Sky to provide its two main sports channels to its competitors)
    • Barclays Bank Plc v Competition Commission (PPI) [2009] CAT 27 (Challenge to Competition Commission's Report on payment protection insurance)
    • Vodafone, Orange, O2 and T-Mobile v Ofcom [2010] EWCA Civ 391 (Court of Appeal; respective jurisdictions of the CAT and the OFT in appeals under the Communications Act)
    • BT v Ofcom [2009] CAT 11 (mobile call termination)
    • Orange Personal Communications Services Ltd v Ofcom [2007] CAT 36 (Ofcom's dispute resolution powers under the Communications Act 2003)
    • H3G v Ofcom [2008] CAT 11 (significant market power in the market for wholesale mobile voice call termination)
    • Vodafone v Ofcom [2008] CAT 22 (mobile number portability)
    • BT v Ofcom (0845/0870 numbers)
    • Crehan v Inntrepreneur Pub Company [2006] UKHL 38 (House of Lords; damages action; status of Commission decisions in national courts)
    • Hutchison 3G UK Ltd v O2, Orange, T-Mobile and Vodafone [2008] EWHC 55 Comm (Commercial Court; pre-action disclosure; Article 81 EC)
    • Argos and Littlewoods v OFT [2006] EWCA Civ 1318 (Court of Appeal; price-fixing)
    • AAH Pharmaceuticals v Pfizer and Unichem [2007] EWHC 565 (High Court; interim injunction; Articles 81 and 82; distribution of pharmaceuticals)
    • OFT's Market Enquiry into distribution of pharmaceuticals. Represented the British Association of Pharmaceutical Wholesalers.
    • Trouw UK Limited v Nippon Soda and Mitsui (Commercial Court; cartel damages claim
    • Independent Schools - price-fixing
  • EU law M

    Marie has acted in many high-profile and diverse EU law cases before the English and European Courts, including acting in challenges to the 2nd Tobacco Products Directive and the UK plain packaging legislation; the Micula ligitation raising the interrelationship between ICSIC arbitration awards and EU law;  aviation cases (Monarch AirlinesTui Travel and IATA); a range of pharmaceutical cases (including PTC Therapeuticspay for delay litigationGMP-Orphan in relation to orphan drugs); asylum and human rights claims (NSEl Kott) and sanctions cases (PMOIBank Saderat).  Marie was a référendaire to Judge Edward at the ECJ, Chair of the Bar European Group between 2016-2018; Visiting Fellow at the Centre for European Law, King’s College, London and a Trustee of the Slynn Foundation.  Notable cases include:

    • R (Monarch Airlines) v Airport Coordinator [2017] EWCA Civ 1892.
    • Micula v Government of Romania [2017] EWHC 31, judgment of CA pending.  Acting for Claimant, instructed by White and Case in enforcement of ICSID Award in circumstances where Commission has determined payment would constitute state aid.
    • Apple v Qualcomm (Article 102 / FRAND claim in relation to licensing by Qualcomm of its chipsets used in Apple devices; judgment on jurisdiction [2018] EWHC 1188 (Pat).  Representing Apple, instructed by Boies Schiller LLP.
    • R (Gureckis and others) v Secretary of State for the Home Department [2017] EWHC 3298 (Admin).  Acted for claimants, instructed by Lambeth Law Centre, in successful challenge to Government policy of deporting EEA nationals found sleeping rough.
    • Case C-267/16 Buhagiar v Ministry of Justice (CJEU; reference from Gibraltar courts re scope of application of the Treaty to Gibraltar).
    • Case T-718/15 PTC Therapeutics v European Medicines Agency; acting for claimant, instructed by Covington and Burling, confidentiality of pharmaceutical information).
    • Case T-733/17 GMP Orphan SA v European Commission (challenge to failure to confer orphan drug designation).
    • Case T-433/15 Bank Saderat v Council and Commission, damages claim on behalf of claimant bank seeking damages for unlawful sanctions imposed by Council, instructed by Stephenson Harwood.
    • Case C-547/14 Philip Morris v Secretary of State for Health, CJEU judgment of 4 May 2016; acted for Philip Morris, instructed by Skadden Arps in challenge to 2nd Tobacco Products Directive.
    • R (British American Tobacco) v Secretary of State for Health [2016] EWHC 1169 (Admin); acted for Philip Morris, instructed by Skadden Arps in challenge to UK plain packaging regulations.
    • ZAT v Secretary of State for Home Department [2016] EWCA Civ 810; acted for UNHCR in appeal concerning rights of unaccompanied child asylum seekers.
    • MSM (Somalia) v Secretary of State for Home Department [2016] EWCA Civ 715; acted for UNHCR in appeal concerning interpretation of Qualification Directive.
    • Mirga v Secretary of State for Work and Pensions [2016] UKSC 1; acted for AIRE Centre in Supreme Court appeal concerning rights to social security of migrant workers.
    • R (W,X,Y and Z) v Secretary of State for Health [2015] EWCA Civ 1034; acted for Secretary of State for Health in successfully resisting challenging to NHS data sharing arrangements.
    • Case C-411/10 NS (CJEU; asylum; effect of EU Charter of Fundamental Rights)
    • Case C-364/11 El Kott (CJEU; rights of Palestinian refugees)
    • EM(Eritrea) v Secretary of State for Home Department [2014] UKSC 12; acted for UNHCR in Supreme Court Appeal relating to Dublin Regulation.
    • Joined Cases C-199/12 and C-201/12 X, Y and Z (CJEU, asylum, sexual orientation)
    • Joined Cases C-403/08 and C-429/08 QC Leisure and others v FA Premier League (CJEU; cross-border broadcasting; intellectual property)
    • Joined Cases C-581/10 and C-629/10 TUI Travel and others v CAA (CJEU; obligations of airlines in event of delays to flights)
    • Case C-281/09 Commission v Spain (CJEU; television advertisting)
    • Case C-512/08 Commission v France (CJEU; free movement, cross-border healthcare)
    • Case C-27/09P France v People's Mojahedin of Iran (CJEU, asset freezing)
    • Case C-420/07 Apostolides v Orams (CJEU; status of the occupied area of Cyprus; conflict of laws)
    • Case T-284/08 People's Mojahedin of Iran (General Court; list designating terrorist organisations; asset freezing; human rights)
    • Case C-336/08 Reinke (CJEU, cross-border healthcare; social security)
    • Case C-142/09 Lahousse (CJEU; transport; free movement)
    • Case C-438/05 Viking Line v International Transport Workers' Federation and Finnish Seamen's Union (CJEU, free movement; right to strike)
    • Case C-344/04 R(IATA) v Secretary of State for Transport [2006] ECR I-403 (CJEU; passenger compensation for cancelled and delayed flights)
    • Case C-506/04 Wilson [2006] ECR I-8613 (CJEU, freedom of establishment for lawyers)
    • Timbrell v Secretary of State for Work and Pensions [2010] EWCA Civ 71 (Court of Appeal; application of Equal Treatment Directive to transsexuals)
    • Interfact Ltd v Liverpool City Council; R v Rainbird and Budimir [2010] EWCA Crim 148 (Court of Appeal; consequence of failure to notify legislation under Technical Standards Directive)
    • Oracle America v M-Tech Data Ltd [2010] EWCA Civ 997 (Court of Appeal; EU trade mark/ free movement)
    • R (Countryside Alliance and others) v HM Attorney General [2007] UKHL 52, [2007] 3 WLR 922 (House of Lords; Challenge to the Hunting Act)
    • REPIC Ltd v Secretary of State for Business, Enterprise and Regulatory Reform [2009] EWHC 2015 (Admin) (EU waste legislation)
    • Liu and others v Secretary of State for the Home Department [2007] EWCA Civ; and W(China) and X(China) v Secretary of State for the Home Department [2006] EWCA Civ 1494 (both Court of Appeal; EU citizenship)
  • Public Law M

    Marie is recommended in the principal directories as a leading advocate in public law and human rights.  Prior to taking Silk she was a member of the Attorney General’s ‘A’ Panel of Counsel.   She acts for both claimant, defendants and NGOs in public claw and human rights cases before the English Courts, the EU Courts and the European Court of Human Rights.  Recent highlights include successfully representing Monarch Airlines in the Court of Appeal in relation to its right to landing slots, and successfully challenging the Government’s policy of deporting EEA nationals found sleeping rough.

    Notable cases include:

    • R (Monarch Airlines Limited) v Airport Coordination Limited [2017] EWCA Civ 1892 (successfully challenged ACL’s decision denying Monarch its valuable landing slots on the ground that it had been placed into administration).
    • R (Gureckis and others) v Secretary of State for the Home Department [2017] EWHC 3298 (Admin).  Acted for claimants, instructed by Lambeth Law Centre, in successful challenge to Government policy of deporting EEA nationals found sleeping rough.
    • R (British American Tobacco) v Secretary of State for Health [2016] EWHC 1169 (Admin); acted for Philip Morris, instructed by Skadden Arps in challenge to UK plain packaging regulations.
    • R (State of Guernsey) v Secretary of State for Environment [2016] EWHC 1847 (Admin); acted for States of Guernsey in dispute with UK Government in relation to fishing rights.
    • Mirga and Samin v Secretary  of State for Work and Pensions [2016] UKSC 1; acted for Aire Centre intervening in Supreme Court appeal relating to social security rights of EU migrants.
    • R (Napp Pharmaceuticals) v Secretary of State for Health [2016] EWHC 1982 (Admin); acted for claimant in challenge to decision of MHRA.
    • R (W,X,Y and Z) v Secretary of State for Health [2015] EWCA Civ 1034; acted for Secretary of State for Health in successfully resisting challenging to NHS data sharing arrangements.
    • ZAT v Secretary of State for Home Department [2016] EWCA Civ 810; acted for UNHCR in appeal concerning rights of unaccompanied child asylum seekers.
    • MSM (Somalia) v Secretary of State for Home Department [2016] EWCA Civ 715; acted for UNHCR in appeal concerning interpretation of Qualification Directive.
    • R (Barda) v Mayor of London [2015] EWHC 3584 (Admin); acted for claimant in challenge to Mayor’s decision to ban protests outside Parliament.
    • EM (Eritrea) v Secretary of State for Home Department [2014] UKSC 12; acted for UNHCR in Supreme Court Appeal relating to Dublin Regulation.
    • AD v Home Office [2015] EWHC 663 (QB); acted for refugee in damages claim against Home Office.
    • R (Cushnie) v Secretary of State for Health [2014] EWHC 3626 (Admin); represented Secretary of State in challenge to NHS (overseas) regulations.
    • Obrey v Secretary of State for Work and Pensions [2013] EWCA Civ 1584; acted for Secretary of State in appeal raising approach at appeal stage to proportionality assessments made by specialist tribunals.
    • Case C-411/10 NS (ECJ; effect of EU Charter of Fundamental Rights)
    • Case C-364/11 El Kott (ECJ; rights of Palestinian refugees)
    • R (Eventech) v TFL (Admin Court; Addison Lee's challenge to TFL's bus lanes policy)
    • Timbrell v Secretary of State for Work and Pensions [2010] EWCA Civ 71 (Court of Appeal; application of Equal Treatment Directive to transsexuals)
    • Interfact Ltd v Liverpool City Council; R v Rainbird and Budimir [2010] EWCA Crim 148 (Court of Appeal; consequence of failure to notify legislation under Technical Standards Directive)
    • R (EM and others) v Secretary of State for Work and Pensions [2010] EWCA Civ 18 (Court of Appeal; Article 14 ECHR; entitlement of psychiatric patients to social security benefits)
    • Case T-284/08 People's Mojahedin of Iran, judgment of 4 December 2008 (General Court; list designating terrorist organisations; asset freezing; human rights)
    • R (Countryside Alliance and others) v HM Attorney General [2007] UKHL 52, [2007] 3 WLR 922 (House of Lords; challenge to the Hunting Act)
    • R (Crest Nicholson) v OFT [2009] EWHC 1875 (Admin) (Challenge to OFT's settlement procedure)
    • AL v Human Fertilisation and Embryology Authority and Secretary of State for Health [2008] EWHC 2149 (Fam) (Article 8 ECHR; fertility treatment; consent requirements)
    • Liu and others v Secretary of State for the Home Department [2007] EWCA Civ; and W(China) and X(China) v Secretary of State for the Home Department [2006] EWCA Civ 1494 (both Court of Appeal; EU citizenship)
    • R (Crouch) v South Birmingham Primary Care Trust and Secretary of State for Health [2008] EWHC 605 (Admin) (NHS arrangements for dentists)
    • R (Compassion in World Farming) v DEFRA [2004] EWCA Civ 1009 (livestock protection legislation)
    • Campbell v Secretary of State for Work and Pensions [2004] 3 All ER 387 (Court of Appeal; Article 9 ECHR)
    • Former King of Greece v Greece 33 EHRR 21 (European Court of Human Rights; Article 1 of Protocol No 1)
    • Hashman and Harrup v UK 30 EHRR 241 (European Court of Human Rights)
  • Publications M
    • References to the European Court (2nd ed, Sweet & Maxwell), Co-author with David Anderson QC.
    • Sports Law (Hart Publishing), Co-author with Michael Beloff QC and Tim Kerr QC (2nd ed, October 2012)
    • Contributor to Judicial Review, Principles and Procedure (OUP, 2013)
    • Contributor to Competition Litigation (OUP)
    • Numerous articles in legal journals
    • Member of the Editorial Boards of World Competition (Kluwer) and International Sports Law Review (Sweet and Maxwell).
  • Qualifications M

    BA, BCL (1st Class) (Oxon)

  • Directory Quotes M
    • "She is absolutely excellent. She was all over the detail, and very friendly and easy to work with." "Careful and rigorous." (Chambers & Partners 2019)
    • "She has an incredible ability to read judges and understand exactly what they need." "She is very responsive, approachable and gives very pragmatic advice. She is very empathetic with vulnerable clients." (Chambers & Partners 2019)
    • "She offers a really powerful strategic view on a case, providing a good overview of the key issues and producing outstanding advocacy." (Chambers & Partners 2019)
    • "She is clearly at the top of her game in European law, offering an outstanding clarity of thought and understanding of the commercial points." (Chambers & Partners 2019)
    • "She was brilliant on an urgent judicial review and delivered a fantastic result for the client." (Legal 500 2018-19)
    • "Formidable advocate and fantastic strategist." (Legal 500 2018-19)
    • "Timely in responding to questions, approachable and easy to work with, constructive, and has a good sense of judgement, including in advocacy." (Legal 500 2018-19)
    • "‘Manages to make the implausible sound plausible, using a very calm measured style." (Legal 500 2018-19)
    • Marie Demetriou QC receives plaudits for her expertise in public law competition cases and her considerable experience working with regulators. She is praised for her “excellent judgement” and is recognised as “one of the leaders in the competition space”. (Who's Who Legal - UK Bar: Competition 2018)
    • "Incredibly responsive and very, very collaborative. Also, the quality of her oral submissions is fantastic. He is very good at drilling into the crux of an issue and presenting it in a way which is really helpful. She is user-friendly and brings a lot of clarity to murky cases." (Chambers & Partners 2018)
    • "Very responsive and very approachable, Marie is quick to get to grips with complex facts. She gives very clear, pragmatic advice and is excellent on her feet." (Chambers & Partners 2018)
    • "She is an exceptionally good barrister to have on the team, with the ability to get on top of the detail quickly and see things from the client's perspective." (Chambers & Partners 2018)
    • "She is a calm and assured performer who gets her points over well." (Chambers & Partners 2018)
    • "Clearly intelligent, with the ability to reduce complex issues to simple ones for the court." (Legal 500 2017)
    • "She has an effective manner in court and is one of her clients’ favourite advocates." (Legal 500 2017)
    • "A calm and assured performer, who gets her points across well." (Legal 500 2017)
    • "Marie Demetriou QC is distinguished by her ability to “cut through complexity” and for her “excellent judgement”. She is standing counsel to the CMA, as well as a popular counsel to commercial clients and other public bodies in complex competition law actions." (Who's Who Legal - UK Bar: Competition 2017)
    • "Marie Demetriou QC is highlighted for her expertise in this area as a “top-tier” competition, EU and public law barrister." (Who's Who Legal - UK Bar: Telecoms 2017)
    • "She's jolly good and does a lot of telecoms work." "A very able advocate." (Chambers & Partners 2017)
    • "Very responsive and very approachable, she is quick to get to grips with the complex facts of a case and gives very clear and pragmatic advice." (Chambers & Partners 2017)
    • "She's gently persuasive and one of the most charming advocates on the stage." "She has a wonderfully conversational advocacy style which anyone can follow." (Chambers & Partners 2017)
    • "Really strong on her feet. She has real weight and presence in court. She can hold her own against unpleasant and aggressive opponents and is also really good with the client. A pleasure to deal with." "A deep understanding and analytically bright. She is utterly charming and quickly establishes a rapport with both judges and clients." (Chambers & Partners 2017)
    • "She carries immense authority in the field of competition litigation and is well known and respected by competition law practitioners. It is very good to be seen having her fighting on your side." (Chambers & Partners 2017)
    • "Marie Demetriou QC is internationally nominated for her practice which comprises significant experience acting for clients in the pharmaceutical and telecommunications sector." (Who's Who Legal - Competition 2017)
    • "A formidable advocate and fantastic strategist." (Legal 500 2016)
    • "Enormously impressive and pitch-perfect in difficult hearings." (Legal 500 2016)
    • "She is effortlessly cool - she doesn't have any nerves or ever get stressed." (Chambers & Partners 2016) 
    • "An extremely personable and client-friendly silk with a stellar reputation for cases which have an EU law aspect." (Chambers & Partners 2016) 
    • "She is outstanding at making the complex simple and really cutting through to the key issues." (Chambers & Partners 2016) 
    • "She is hugely clever and a very logical thinker who is very easy to work with." "She is very legally astute and knowledgeable, particularly in EU and human rights law, where she adds a lot of value." (Chambers & Partners 2015) 
    • "She is excellent and extremely easy to work with. She is very approachable, and pragmatic in coming to a solution that will make everybody happy." "Very easy-going and relaxed, but also very efficient in the way she goes about her work, and very sharp when it comes to European law." (Chambers & Partners 2015)
    • "Absolutely outstanding." "She is very easy to work with and very responsive." (Chambers & Partners 2015)
    • “Earns praise from clients for her proactive approach to client service. She is particularly appreciated for her ability to explain complex issues in a concise yet effective manner.” (Chambers & Partners 2015) 
    • "I found her EU legal expertise to be second to none." "She was extraordinarily impressive and responsive. She has a high degree of commitment and flexibility, meaning she is ready to comply with tight deadlines." (Chambers & Partners 2015) 
    • "She's smart and user-friendly, and performs well on telecoms competition matters." (Chambers & Partners 2015) 
    • "Fiercely bright and strategic." (The Legal 500 2014)
    • "Instructing solicitors are gushing in their praise of Marie Demetriou. Fantastically bright, and a pleasure to work with," she offers "sound, pithy advice, is a team player and is someone clients trust and like." (Chambers UK 2012)
    • "Marie Demetriou is "a highly intellectual barrister who is the most pragmatic of performers." Solicitors favour her as "she takes absolutely everything into account in a case," and approaches matters in a "persuasive, measured and calm" manner. (Chambers UK 2012)
    • "Marie Demetriou is ‘an iron fist in a velvet glove'" (Legal 500 2011)
    • "Marie Demetriou gives ‘clear and concise practical advice'" (Legal 500 2011)
    • "a great force to have on your side for all public and EU matters" (Chambers & Partners 2011)
    • "untiring" and "terribly bright and ever so good to work with" and has "notable experience of acting for central government, corporations and individuals in high-profile judicial review challenges" (Chambers & Partners 2011, Administrative & Public Law,)
    • "absolutely fantastic", "superb drafting", "very good insight" (Legal 500 2010, EU and competition)
    • "bright, quickly grasps complex issues and is generally a pleasure to work with" (Chambers & Partners 2010, Competition/European Law)
    • "Clients consider her one of the fastest-rising juniors at the Bar, viewing her as someone who ‘fights hard for clients, often against the toughest of odds'" (Chambers & Partners 2010, Telecommunications)
    • "impeccable intellect and extremely charming demeanour."; "professional manner and magnificent understanding of Competition and EU law,"; "she knows intimately how the European court functions, which is always a plus" (Chambers & Partners, 2009)
    • "displays excellence due to her superb knowledge of the European courts" (Chambers & Partners, 2009)
    • remarked upon for her flexibility and superlative grasp of competition and general European law issues (Chambers & Partners, 2008)