Mari Rosser

Partner, Head of Medical Negligence

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Mari Rosser is Head of Medical Negligence. Her main area of expertise is clinical negligence; she is a member of both The Law Society’s clinical negligence panel and the referral panel for Action against Medical Accidents. Mari has a particular specialism in both child and adult brain injury cases, and fatal accident claims. She has advised a number of patients who have been victims of gross neglect, representing the interests of patients and bereaved families in such cases involving GMC proceedings.

Mari is head of a team which advises and assists the Welsh Community Health Councils (CHCs) on all aspects of medical law.  She has been providing legal advice and support to the CHCs since the firm’s appointment as the CHCs’ solicitors in 2004. She has advised the CHC Board, Chief Officers and advocates on a variety of complex issues of public and medical law.

Mari has also provided training to Chief Officers and Complaints Advocates on a variety of subjects. She has  lectured at the annual AvMA Patient Safety Conference in Wales  and on the Cardiff Nursing and Midwifery studies course.

Mari is recommended by both the Legal 500 and Chambers directories as a leader in the field of clinical negligence.

She has written  articles for the Journal of Personal Injury Lawyers and Clinical Risk.

Mari is also a regular media contributor commenting (in Welsh and English) on matters relating to Health law and Clinical Negligence. She is regularly consulted by organisation such as APIL , AvMA and the Law Society on issues arising out of the Welsh NHS complaints procedure – Putting Things Right.


  • Brain injury
  • Spinal injury
  • Catastrophic injury
  • Fatal accidents
  • Obstetric cases
  • Surgical injury

Career history

  • Qualified: 1992
  • Partner at Hugh James: 2001
  • Consultant at Hugh James: 2007
  • Partner at Hugh James: 2011
  • Head of Medical Negligence: 2017



Mari has recently settled:

  • a case involving an above knee amputation following negligent vascular care – damages exceeded half a million pounds.
  • a fatal case involving the delay in diagnosis of a brain tumour.
  • a spinal injury case where the client suffered catastrophic injury  as a result of negligent spinal decompression surgery
  • a fatal case involving delay in diagnosis of meningitis
  • psychiatric case arising out of a failure to appropriately consent a patient prior to  mastectomy surgery

Mari Rosser is considered to be “one of the main players in this field” by market sources. She is “highly experienced and very skilled” in handling high-value and complex matters, including brain and spinal injury matters
Chambers UK 2017



  • Law Degree, Aberystwyth University, 1988
  • Law Society Finals, 1989


  • Welsh

What do you like to do outside work?

Keep fit, cooking, reading and gardening.


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