Aidan O'Brien

Thorough, knowledgeable, very responsive and personable…

Avinder Sidhu, Senior Associate, Kennedys (Clinical Negligence Department)

Aidan O’Brien is instructed to attend multi-track trials, applications and case management conferences on a daily basis.  His work is evenly split between Claimants and Defendants.

Aidan enjoys a broad practice base, with a particular emphasis on high-value Clinical Negligence, Personal Injury, Probate (Wills & Trusts) and Commercial matters.

In addition to his Court work, Aidan has a busy paperwork practice, providing a swift turn-around for pleadings as well as advice on prospects, tactics and quantum.  Aidan regularly represents clients at RTMs and Mediations.

Clinical Negligence

Aidan enjoys an extensive medical practice, ranging from complex clinical negligence claims, regulatory discipline and medical product liability. He has a Master’s degree in Healthcare Law & Ethics and has been published in the British Medical Journal.

Aidan represents both Claimants and Defendants (NHS Resolution and Medical Defence Organisations) in the full panoply of negligence claims.

Aidan has particular expertise in claims arising from:

  • Missed cancer diagnoses.
  • Cauda Equina Syndrome.
  • Lack of informed consent.
  • Obstetric injuries, including shoulder dystocia.
  • Compartment syndrome.
  • Surgical mistakes, including those resulting in paralysis.
  • Hypoxic brain injuries.
  • Pressure sores.
  • Nervous shock.

Recent instructions include as sole counsel:

  • Cauda equina syndrome claim, valued at >£2.5 million.
  • Defending a claim alleging that the improper use of a vaccine led to chronic fatigue syndrome, pleaded at >£7 million.
  • Claims arising from allegations of negligent delivery due to excessive traction, causing Erb’s palsy and life-long disabilities, pleaded at >£3.7 million.
  • Claim arising from the development of chronic kidney disease following the improper use of medication, pleaded at > £5 million.
  • Various high-profile claims arising from inappropriate surgery and lack of informed consent, arising from an Orthopaedic Surgeon in private practice.
  • Claim arising from a ‘never event’ involving the removal of the wrong bone during surgery.

Aidan is also trained as a Nursing & Midwifery Council Case Presenter and has experience in a wide range of medical regulatory hearings. Aidan also accepts instructions in relation to Court of Protection matters, including withdrawal of treatment and welfare applications.


Aidan is a member of Chambers’ Sports Disciplinary and Regulatory Group. He has substantial experience in a wide range of regulatory hearings ranging from educational, sporting, medical and other professional matters. He frequently advises clients on merits, tactics and procedural matters as well as representing them before a wide range of tribunals.

Aidan sits as a Judicial Panel Chairman for the Rugby Football Union (‘RFU’). His role involves adjudicating on disciplinary issues and competition appeals arising from levels 1-4 of the game (Premiership, Championship and National Leagues 1 & 2).

Aidan has also been appointed as a Judicial Chairman for European Professional Cup Rugby (‘ECPR’) and is qualified to sit on World Rugby disciplinary panels.

As a Judicial Panel Member for the RFU Aidan is heavily involved in sporting regulation both as an Adjudicator and representative counsel. He has a keen sporting interest and understands the culture and values expected within a broad range of sporting contexts.

Aidan also specialises in representing students in respect of academic appeals relating to secondary, tertiary and vocational studies. He regularly represents students at disciplinary hearings, arising from accusations of misconduct, ranging from plagiarism, collusion and sexual misconduct.  Aidan was recently interviewed for a Radio 4 documentary relating to university misconduct hearings.

Aidan also has extensive experience in medical regulatory hearings (GMC, GDC & NMC) as well as a wide range of other professions. He also provides written advice on all aspects of regulatory law.


Aidan regularly acts on behalf of individuals, large businesses and insurance companies in a wide range of high value commercial and contractual disputes. He is frequently instructed to advise on complex issues of law and is lauded for his clear-sighted grasp of practical and commercial considerations.

Aidan regularly advises on complex issues of insurance law and provides readily comprehensible guidance to his clients. He is noted for his effective courtroom advocacy, especially when dealing with intricate legal issues.

Aidan has a particular interest in dealing with fraudulent claims and has experience of complicated multi-track disputes.

Personal Injury

Aidan acts for both claimants and defendants in all aspects of high value personal injury litigation, including employer’s liability, occupier’s liability, slip & trips and road traffic accidents. He is recommended for his incisive advocacy and grasp of complex legal issues.

Civil Fraud

Aidan has dealt with a number of contempt hearings in the High Court, following findings of dishonesty and intentional breaches of court orders.

Aidan also has significant experience of claims involving fraudulent misrepresentation.  In the case of Kadir v Thompson, Aidan successfully challenged the enforceability of a credit hire claim, at first instance and on appeal, on the basis that the hire organisation had made fraudulent misrepresentations regarding a claimant’s liability to pay sizable credit hire charges.

Sports Law

Aidan is a member of Chambers’ Sports Disciplinary and Regulatory group.

In September 2014, Aidan was appointed as a Judicial Panel Member for the Rugby Football Union. His role involves adjudicating on disciplinary issues and competition appeals arising from levels 1-4 of the game (Premiership, Championship and National Leagues 1 & 2). Aidan therefore has extensive experience as an Adjudicator and as representative counsel in sporting disputes.

Aidan also accepts instructions on the full panoply of sporting legal matters, including but not limited to contractual, commercial, competition, media, employment and injury based disputes.

Trusts & Probate

Aidan accepts instructions in relation to all aspects of contentious trust and probate matters. He has particular expertise in:

  • Claims under the Inheritance (Provision for Family and Dependents) Act 1975;
  • Challenging the validly of wills (formalities, lack of capacity, knowledge & approval, undue influence and fraud);
  • Proprietary estoppel;
  • Secret trusts;
  • Mutual wills;
  • Third party interests in property;
  • Mental capacity issues (Court of Protection, LPAs, EPAs & statutory wills).

If you would like to instruct Aidan O’Brien or would like help or advice in doing so, please call and talk to our excellent clerking team, led by Chief Executive, Alan Kilbey MBE. Our phone number is +44 (0)20 7583 9241. Alternatively, please email us at

For more information about our clerking team, please click here for the clerks page.

Appointments & Memberships

  • Rugby Football Union Judicial Panel.
  • British Association for Sport & Law.
  • Personal Injuries Bar Association.
  • London Common Law & Commercial Bar Association.
  • Association of Regulatory & Disciplinary Lawyers.
  • Association of Contentious Trust and Probate Specialists ‘ACTAPS’

Education & Qualifications

  • BPTC, City Law School, London.
  • MA Healthcare Law & Ethics, University of Manchester.
  • BA Law & Politics, University of Manchester.
  • St Colman’s College Grammar School, Newry, Northern Ireland.


I have had the pleasure of working with Aidan for the last four/five years. Aidan is an excellent barrister and in my view, stands out from other barristers because of his attention to detail and his quick thinking when faced with a difficult situation. Aidan also goes the extra mile with the witnesses, to make them feel at ease and keeping me happy at the same time.

Recently, we attended a Trial together. I normally pride myself in my attention to detail but Aidan spotted something that I had not and, as a result, got us out of what could have been a very sticky situation. Following the Trial, although we settled, the witness told me how impressed he was with Aidan; in particular the calm manner in which he dealt with the situation and the way Aidan made him feel at ease.

Aidan is also very helpful when it comes to “non fee” work and has carried out a number of seminars for my firm and is always happy to help. Recently I managed to persuade him to undertake the Three Peaks Challenge with me! I am not sure Aidan has forgiven me for that yet! I look forward to working with Aidan in the future.

Narrinder Taggar


Shakespeare Martineau


At DWF, my causation team and I have worked with Aidan over the past few years  and he has provided exceptional success with his advocacy. We believe that he is thorough, evidences strong technical ability, is enthusiastic and is well liked by our clients.

Jewels Chamberlain

Director, Fraud & Insurance Team



Thorough, knowledgeable, very responsive and personable…

Avinder Sidhu

Senior Associate, Clinical Negligence Department



Approachable and very client friendly. Knowledgeable in the area of contentious probate in which I would not hesitate to instruct Aidan again.

Tracey Leathley

Specialist Probate Solicitor

Lyons Davidson




  • The British Medical Journal: ‘Lessons from the Ashya King case’.
  • The Guardian: ‘Nothing but the Truth’.
  • Farrar’s Building Website: ‘Consent to Medical Treatment – Montgomery v Lanarkshire Health Board’
  • Farrar’s Building PI Update: ‘Accidents Abroad: Jurisdiction, Liability and Damages’
  • Employment Law Update 2014: ‘Third Party Harassment after the Repeal of S.40 EqA’.
  • Farrar’s Building EL Seminar ‘S. 69 of the Enterprise and Regulatory Reform Act 2013’