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Mark O’Brien O’Reilly (Pupil)

Mark O'Brien O'Reilly

Year of call: 2021

Practice areas: Planning, Environment, Compulsory Purchase and Compensation, Local Government, Public Law

Mark O’Brien O’Reilly (Pupil)


Mark is currently a second six pupil under the supervision of Melissa Murphy QC. During the first four months of pupillage Mark was under the supervision of Richard Honey QC. Mark welcomes instructions across all of Chambers’ practice areas, with a particular interest in planning, environmental and public law. Mark’s in-depth knowledge of international environmental law gained during his LLM at the University of Cambridge has proved of considerable assistance during his pupillage. Mark has assisted with several judicial reviews concerning the Paris Agreement, the Climate Change Act 2008, international human rights and other climate change related matters.  Mark is a member of the Attorney General’s ‘Junior’ Junior Scheme and is happy to accept instructions through the scheme.



Mark assisted at a section 247 stopping up and diversion order inquiry which raised several issues, including parking, highway safety and impact upon heritage assets. 

Mark also assisted at a planning inquiry dealing with inappropriate development (a gypsy/traveller site) in the Green Belt and within an Area of Outstanding Natural Beauty. The inquiry was concerned with an appeal against a refusal of planning permission and also with an appeal against an enforcement notice. 

Mark has assisted at a planning inquiry considering the merits of a large residential development in a semi-rural location. The inquiry considered the impact upon character and appearance, the impact upon a Grade II* listed building, highway safety and biodviersity. 

Mark assisted with a two day judicial review challenging the decision of the Minister of State for Housing to grant planning permission for the UK Holocaust Memorial and Learning Centre next to the Houses of Parliament. 

Mark has written draft Advices on a number of issues, including enforcement notices, appeals against enforcement notices, immunity from enforcement action, changes of use, prior approval and permitted development rights, the precautionary principle and the scope of amendments under section 73 of the Town and Country Planning Act 1990. He also assisted with preparations for defending a judicial review challenging a Special Development Order. 

Environmental Law

Mark has gained extensive experience of environmental law and is a frequent contributor to FTB’s Environmental Law Blog. 

Mark assisted with defending a judicial review brought by Plan B Earth and four claimants challenging the lawfulness of the government’s action on climate change as breaching sections 13 and 58 of the Climate Change Act 2008 and section 6 of the Human Rights Act 1998 by way of the ECHR (Articles 2, 8, and 14). The Court was also required to address the status of the Paris Agreement as an unincorporated international treaty. 

Mark assisted with defending a complex and high profile three day judicial review before the Divisional Court in which Friends of the Earth challenged the decision of UK Export Finance, along with the prior approval of the Secretary of State for International Trade and the Chancellor of the Exchequer, to provide up to US$1.15bn in export finance and support for a US$20bn liquified natural gas field in Northern Mozambique. The judicial review was primarily concerned with the Paris Agreement. 

Mark assisted with preparations for defending several judicial review challenges brought by NGOs to the government’s Net Zero Strategy. 

Mark has also gained experience of dealing with the SEA and EIA Directives and Regulations and the Aarhus Convention. 

Public Law

Mark has gained experience across a wide range of public law areas and has assisted with judicial reviews raising both substantive and procedural public law issues, including the public sector equality duty and the doctrine of legitimate expectation.  Mark is a member of the Attorney General’s ‘Junior’ Junior Scheme and is happy to accept instructions through the scheme.

Community Infrastructure Levy

Mark assisted with a two day judicial review concerning social housing relief under the Community Infrastructure Levy Regulations 2010 and the consequences of a failure to submit a commencement notice. 

Compulsory Purchase/Compensation

Mark has assisted with a wide range of compulsory purchase and compensation matters. During the course of his pupillage, he has attended several conferences dealing with compulsory purchase and compensation cases. He has gained experience of a number of complex issues, including transfer of trade, compensation for disturbance, the compulsory acquisition of open space, potential exchange land sites and the applicability of Bishopgate.  

Mark assisted with a mediation in respect of a multi-million claim for compensation. 

Other Work

Mark assisted with a claim for compensation pursuant to the powers conferred upon the Environment Agency by the Water Resources Act 1991. The claim was subject to Early Neutral Evaluation. 


  • BCL Law with History 2019, University College Dublin, First Class Honours 
  • LLM (Master of Law), University of Cambridge, October 2020 – June 2021, First Class Honours. Papers included International Environmental Law
  • Bar Professional Training Course, September 2019 – August 2020, BPP University Law School, Outstanding

Awards and Accomplishments

  • Awarded the Reid Scholarship by Gray's Inn, a Senior Scholarship for Pupillage which is the Inn's most prestigious scholarship and awarded to a pupil barrister of exceptional merit
  • Elected by the Governing Body of Queen’s College, Cambridge to a Foundation Scholarship
  • Awarded a full scholarship plus maintenance (the Snowdon Cambridge Scholarship 2020) by the Cambridge Trust to undertake an LLM (Master of Law) at the University of Cambridge
  • The Baroness Hale of Richmond BPTC Scholarship 2019, awarded by The Honourable Society of Gray's Inn, is the Inn’s newest and most prestigious scholarship. It is awarded to candidates of exceptional merit
  • The BPTC Advocacy Scholarship 2019 is awarded by BPP University Law School to those who demonstrate an outstanding aptitude for advocacy
  • The Career Commitment Scholarship 2019 is awarded by BPP University Law School to those who are considered to be the most promising future legal professionals
  • The Jomati Foundation Bursary 2019, awarded by the Jomati Foundation, assists students of high academic ability with the costs of qualifying as a barrister
  • The Hebe Plunkett Award 2019, awarded by The Honourable Society of Gray's Inn
  • Irish Law Student of the Year 2019 awarded at the Irish National Law Awards in recognition of academic, professional and personal achievements
  • The Gold Medal for Mooting 2017 which is awarded by the University College Dublin Law Society to the student most successful in mooting in the previous academic year
  • Certificate in Work Related Learning (Commercial Law in the City of London) 2017 awarded by the University College Dublin Career Development Centre

Mooting, Debating and Other Advocacy Experience


  • Winner of the 2021 Cambridge University Human Rights Law Moot
  • Winner of the 2018 Irish National Moot Court Competition which was judged by a Supreme Court and High Court judge
  • Winner of the 2017 Silken Thomas National Moot Court and the 2016 Vivian Lavan Moot Court Competition, which were judged by a District and Circuit Court Judge respectively 
  • Best Advocate of the 2017 Cecil Lavery Moot Court 
  • Runner-up of the 2016 University College Dublin Pro-Am Moot Court 
  • Semi-finalist of the 2017 National Moot Court Competition, the 2016 University College Cork Moot Court Open and the 2017 Cecil Lavery Moot Court 
  • Attended a Stetson Law School advocacy training course on the art of mastering cross examination in July 2017 
  • Invited to judge several mooting competitions at the University of New South Wales

Debating and public speaking

  • Addressed the launch of the University College Dublin Sutherland Opportunity in December 2019, a new scholarship opportunity providing financial support to enable students from under-represented groups to pursue a career in law
  • Winner of the 2016 National De Valera Cup for Debating 
  • Finalist of the 2015 University College Dublin Intervarsity Novice Debating Competition 
  • Semi-finalist of the 2016 Irish Times National Debating Competition 
  • Semi-finalist of the 2015 James Joyce Maidens' Debating Competition 
  • Represented the University College Dublin Law Society as a judge at the European Universities Debating Championships in August 2016 
  • Participated in various international debating competitions 
  • Spoke in several house debates at university 
  • Captain of the St Patrick’s Classical School debating team 
  • Chosen to act as valedictorian at school graduation ceremony due to public speaking ability and academic achievements 


  • Winner of the European Law Students’ Association Maynooth International Negotiation Competition in March 2019. As part of team of two, defeated a team from Georgetown University, Washington D.C. in the final 
  • Finalist of the University College Dublin Student Legal Service McCann FitzGerald Commercial Negotiation Competition in November 2017, having previously been a semi-finalist in November 2016 


  • The Case for the Recognition of the Right to a Healthy Environment at the International Level, FTB Environmental Law Blog
  • M O’Brien O’Reilly, ‘Divorce and the Constitution: An Unhappy Union?’, University College Dublin Student Legal Service Journal: Challenging the Status Quo: Student Perspectives on Law Reform (2019) 
  • M O’Brien O’Reilly, ‘The Election, and Constitutional Role, of the President of Ireland’, University College Dublin Student Legal Service Journal: 80 Years of Bunreacht na hÉireann (2018) 
  • M O’Brien O’Reilly, ‘The Rule of Law in the EU and the Polish question’, University College Dublin Student Legal Service Journal: Legal Effects of the European Union (2017) 
  • M O’Brien O’Reilly, ‘Challenging a Referendum’, University College Dublin Student Legal Service Journal: Public Interest Law in Ireland (2016) 


  • Constitutional & Administrative Law Bar Association (ALBA) 
  • UK Environmental Law Association (UKELA)
  • London Irish Lawyers Association

Other Relevant Work Experience

  • Occasional Lecturer at Maynooth University, September 2021
  • Executive Assistant to the Director of Summer at UCD, University College Dublin Estates Services (summer 2019)
  • Mark spent time working as a vacation scheme student at leading law firms including Freshfields Bruckhaus Deringer, Mason Hayes & Curran LLP and Herbert Smith Freehills where he worked on large-scale, long-term infrastructure and energy projects

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