Arianna Kelly

Arianna is a leading junior in the Court of Protection (Chambers and Partners and Legal 500). Her practice spans a wide range of complex welfare and serious medical treatment cases, often involving the overlap between public law, mental health, and mental capacity. She is regularly instructed in cross-jurisdictional matters involving personal injury and the Court of Protection. Arianna also acts in cases under the inherent jurisdiction of the High Court, including both adults and those concerning the deprivation of liberty of children and young people, and has been involved in a number of leading cases in this field. Arianna is a contributing author to Court of Protection Practice (Lexis Nexis) and a contributing editor to the 39 Essex Chambers Mental Capacity Reports. She is also a member of the National Committee of the Court of Protection Practitioners Association.

Arianna is available for out-of-hours work. She has an increasing focus on medical treatment cases and has acted in multiple cases involving the withdrawal of life-sustaining treatment.

“Arianna is just superb. Her advocacy is engaging and thorough and her drafting is excellent and to the point.” Chambers and Partners 2025 (Court of Protection: Health and Welfare)

“Arianna is a fantastic barrister whose knowledge of the Care Act is a huge asset to COP cases. She is always willing to help out on cases and can turn cases around quickly, providing great advice on complex issues in short timeframes." Legal 500 2023 (Court of Protection and Community Care)

Cases of note

• J v Bath and North East Somerset Council [2025] EWCA Civ 478 - Sole junior counsel to substantively address the Court of Appeal on a leading case relating to the authorisation of deprivations of liberty of children under Article 5 ECHR for children in care.
• E & F (Minors: Blood Transfusion) [2021] EWCA Civ 1888 - Junior counsel for a health trust in the Court of Appeal on the leading case on applications in the inherent jurisdiction for the medical treatment of minors.
• Re PQ (Court Authorised Dol : Representation During Review Period [2024] EWCOP 41 (T3) Sole counsel in for the applicant local authority in the leading case on Article 5(4) ECHR rights to representation during the pendency of a court-authorised deprivations of liberty in the Court of Protection.
• NHS South East London Integrated Care Board v JP & Ors [2025] EWCOP 8 (T3) and [2025] EWCOP 4 (T3) Sole counsel for the applicant ICB a serious medical treatment application relating to a man who had been in a prolonged disorder of consciousness condition for 9 years after experiencing a brain injury. The second judgment in this matter considered how applications of this nature should be brought before the court, and wider systemic issues for the care and treatment of PDOC patients.
• Manchester University NHS Foundation Trust v JS [2023] EWCOP 12 - Sole counsel for the Secretary of State for Health and Social Care in a leading authority on Schedule 1A ineligibility for detention under the Mental Capacity Act 2005.
• Bolton Council v KL [2022] EWCOP 24 - Acted on behalf of a local authority in an application defining the test for streamlined applications for deprivations of liberty. Before Her Honour Judge Hilder.
• Guy’s & St Thomas’ NHS Foundation Trust and Royal Borough of Greenwich v M, F, and R [2021] EWHC 2377 (Fam) - Acted on behalf of the child’s guardian in an application to withdraw life-sustaining treatment. Before Mr Justice Cobb.
• Re Z (Medical Treatment: Invasive Ventilation) [2021] EWHC 2613 (Fam) - Acted on behalf of a father of a child contesting an application by a health trust to set a ceiling of care for a child with serious illness, with the child not to be offered invasive ventilation. Before Mr Justice Peel.

Arianna is a qualified mediator with a keen interest in the use of mediation in Court of Protection health and welfare and property and affairs contexts.

Arianna acts and advises in all areas of property and affairs work, acting regularly for the Office of the Public Guardian, deputies and private individuals. She has a particular interest in matters with a crossover between property and affairs and social care charging, and is the author of the leading text on social care charging. Arianna is particularly experienced in issues of financial abuse, contested issues relating to capacity, the removal of holders of lasting powers of attorney and statutory wills applications. Arianna regularly advises deputies on applications to the Court of Protection relating to the recovery of funds on behalf of people lacking capacity, including on complex questions of best interests in relation to pursuing recovery from family members. Arianna is a member of the National Executive Committee for the Court of Protection Practitioners Association.

Cases of note

• Calderdale MBC v AB [2021] EWCOP 55 - Acted on behalf of a local authority in an application relating to a property and affairs deputy’s scope of authority. Before Her Honour Judge Hilder.
• Personal injury proceedings - Advised on the scope of a deputy’s duties in personal injury proceedings, considering mixed issues of property and affairs and health and welfare.
• Removal of holders of lasting power of attorney - Acted on behalf of the Office of the Public Guardian in an application to remove holders of a lasting power of attorney and appoint a panel deputy, on the basis of the donor making substantial transfers of assets while the donor had capacity.
• Access to P - Acted on behalf of a deputy to secure access to a vulnerable person. Arianna supported the deputy in making an emergency application to the Court of Protection to ensure the deputy had access to P in order to discharge her duties.
• Double Recovery - Provided detailed advice in proposed judicial review proceedings relating to eligibility for local authority funding where P had significant periodical payments.
• Recovery of Assets - Advised a deputy on what steps could be taken to restore P’s estate following the removal of her former attorneys;. The advice was written both to advise the deputy and support an application to the Court of Protection for permission to bring litigation.
• Ending a deputyship - Acted on behalf of a person who had a property and affairs deputy appointed following a brain injury, but had regained capacity and sought the discharge of his deputy. 

Arianna regularly acts and advises in matters relating to the inherent jurisdiction of the High Court. Arianna is available for urgent or out-of-hours applications in both Court of Protection and inherent jurisdiction applications.

Arianna is a leading junior in the Court of Protection (Chambers and Partners and Legal 500). Her practice spans a wide range of complex welfare and serious medical treatment cases, often involving the overlap between public law, mental health, and mental capacity. She is regularly instructed in cross-jurisdictional matters involving personal injury and the Court of Protection. Arianna also acts in cases under the inherent jurisdiction of the High Court, including both adults and those concerning the deprivation of liberty of children and young people, and has been involved in a number of leading cases in this field. Arianna is a contributing author to Court of Protection Practice (Lexis Nexis) and a contributing editor to the 39 Essex Chambers Mental Capacity Reports. She is also a member of the National Committee of the Court of Protection Practitioners Association.

Arianna is available for out-of-hours work. She has an increasing focus on medical treatment cases and has acted in multiple cases involving the withdrawal of life-sustaining treatment.

“Arianna is just superb. Her advocacy is engaging and thorough and her drafting is excellent and to the point.” Chambers and Partners 2025 (Court of Protection: Health and Welfare)

“Arianna is a fantastic barrister whose knowledge of the Care Act is a huge asset to COP cases. She is always willing to help out on cases and can turn cases around quickly, providing great advice on complex issues in short timeframes." Legal 500 2023 (Court of Protection and Community Care)

Cases of note

• J v Bath and North East Somerset Council [2025] EWCA Civ 478 - Sole junior counsel to substantively address the Court of Appeal on a leading case relating to the authorisation of deprivations of liberty of children under Article 5 ECHR for children in care.
• E & F (Minors: Blood Transfusion) [2021] EWCA Civ 1888 - Junior counsel for a health trust in the Court of Appeal on the leading case on applications in the inherent jurisdiction for the medical treatment of minors.
• Re PQ (Court Authorised Dol : Representation During Review Period [2024] EWCOP 41 (T3) Sole counsel in for the applicant local authority in the leading case on Article 5(4) ECHR rights to representation during the pendency of a court-authorised deprivations of liberty in the Court of Protection.
• NHS South East London Integrated Care Board v JP & Ors [2025] EWCOP 8 (T3) and [2025] EWCOP 4 (T3) Sole counsel for the applicant ICB a serious medical treatment application relating to a man who had been in a prolonged disorder of consciousness condition for 9 years after experiencing a brain injury. The second judgment in this matter considered how applications of this nature should be brought before the court, and wider systemic issues for the care and treatment of PDOC patients.
• Re MK (Deprivation of Liberty and Tier 4 Beds) [2024] EWHC 1553 (Fam) Acted for a mental health trust and NHS England in a case considering the Article 2 and 3 ECHR obligations on acute and mental health trusts to children with high needs arising out mental health conditions and trauma.
• Manchester University NHS Foundation Trust v JS [2023] EWCOP 12 - Sole counsel for the Secretary of State for Health and Social Care in a leading authority on Schedule 1A ineligibility for detention under the Mental Capacity Act 2005.
• W(Young Person: Unavailability of Suitable Placement) [2021] EWHC 2345 (Fam) - Acted on behalf of a health trust in relation to authorise a 15-year-old child’s deprivation of liberty in hospital and in an unregistered community placement. Before Mrs Justice Knowles.
• Bolton Council v KL [2022] EWCOP 24 - Acted on behalf of a local authority in an application defining the test for streamlined applications for deprivations of liberty. Before Her Honour Judge Hilder.

Arianna is a leading junior in the Court of Protection (Chambers and Partners and Legal 500). Her practice spans a wide range of serious medical treatment cases, often involving the overlap between public law, mental health, and mental capacity. She is regularly instructed in cross-jurisdictional matters involving personal injury and the Court of Protection. Arianna also acts in cases under the inherent jurisdiction of the High Court, including both adults and those concerning the deprivation of liberty of children and young people, and has been involved in a number of leading cases in this field. Arianna is a contributing author to Court of Protection Practice (Lexis Nexis) and a contributing editor to the 39 Essex Chambers Mental Capacity Reports. She is also a member of the National Committee of the Court of Protection Practitioners Association.

Arianna is available for out-of-hours work. She has an increasing focus on medical treatment cases and has acted in multiple cases involving the withdrawal of life-sustaining treatment.

“Arianna is just superb. Her advocacy is engaging and thorough and her drafting is excellent and to the point.” Chambers and Partners 2025 (Court of Protection: Health and Welfare)

“Arianna is a fantastic barrister whose knowledge of the Care Act is a huge asset to COP cases. She is always willing to help out on cases and can turn cases around quickly, providing great advice on complex issues in short timeframes." Legal 500 2023 (Court of Protection and Community Care)

Cases of note

• E & F (Minors: Blood Transfusion) [2021] EWCA Civ 1888 - Junior counsel for a health trust in the Court of Appeal on the leading case on applications in the inherent jurisdiction for the medical treatment of minors.
• Nottinghamshire Healthcare NHS Foundation Trust v MC [2025] EWHC 920 (Fam) Acted on behalf of a patient in a high security psychiatric hospital in a contested application as to whether certain medical treatment fell within the scope of the Mental Health Act 1983.
• NHS South East London Integrated Care Board v JP & Ors [2025] EWCOP 8 (T3) and [2025] EWCOP 4 (T3) Sole counsel for the applicant ICB a serious medical treatment application relating to a man who had been in a prolonged disorder of consciousness condition for 9 years after experiencing a brain injury. The second judgment in this matter considered how applications of this nature should be brought before the court, and wider systemic issues for the care and treatment of PDOC patients.
• Re MK (Deprivation of Liberty and Tier 4 Beds) [2024] EWHC 1553 (Fam) Acted for a mental health trust and NHS England in a case considering the Article 2 and 3 ECHR obligations on acute and mental health trusts to children with high needs arising out mental health conditions and trauma.
• Manchester University NHS Foundation Trust v JS [2023] EWCOP 12 - Sole counsel for the Secretary of State for Health and Social Care in a leading authority on Schedule 1A ineligibility for detention under the Mental Capacity Act 2005, considering how detentions in hospital for the purpose of treating mental disorders may be authorised.
• Barnet Enfield And Haringey Mental Health NHS Trust & Anor v Mr K & Ors [2023] EWCOP 35 – Acted as sole counsel for a mental health trust in a complex matter authorising assessment and treatment of a man in the community; this judgment is noted the scope of the powers of the Court of Protection to make interim declarations on capacity and best interests.
• Guy’s & St Thomas’ NHS Foundation Trust and Royal Borough of Greenwich v M, F, and R [2021] EWHC 2377 (Fam) - Acted on behalf of the child’s guardian in an application to withdraw life-sustaining treatment. Before Mr Justice Cobb.
• Re Z (Medical Treatment: Invasive Ventilation) [2021] EWHC 2613 (Fam) - Acted on behalf of a father of a child contesting an application by a health trust to set a ceiling of care for a child with serious illness, with the child not to be offered invasive ventilation. 

Arianna is a leading junior in both Administrative and Public Law (Legal 500) and Community Care (Chambers and Partners). She acts in a wide range of public law judicial review matters and is B panel counsel for both the Attorney General and Equality and Human Rights Commission (EHRC). She regularly advises public authorities on policies relating to health and social care. She sits as a Family Recorder, First-tier Tribunal Judge (Mental Health), and Court of Protection Judge, and regularly acts and advises in a range of judicial reviews and public law matters concerning the Mental Health Act 1983 and Children Act 1989.

Arianna works extensively in community care, advising local authorities, NHS bodies, and national public bodies on both policy and individual matters relating to health, social care, and mental health. She frequently undertakes judicial reviews in areas including eligibility and care planning, community care charging, safeguarding investigations, and provider de-registration. She is the author of Social Care Charging, the leading text in this area, and is noted by Legal 500 for her “Outstanding knowledge of the Care Act.”

Legal 500 writes: “Arianna is a superb advocate. She is methodical in her reasoning and makes complex concepts straightforward to understand. She works really hard and is always someone you want fighting your corner. She has star quality about her.”

• “A junior who is well respected by judges, and has phenomenal attention to detail.’ Legal 500 2025 (Administrative and Public Law)

• "She is responsive, thoughtful, practical, empathetic, academic and meticulously well prepared. She is brave on her feet, argues difficult points elegantly and works tirelessly hard for her vulnerable clients." Legal 500 2024 (Administrative and Public Law)

• ‘Arianna is extremely reliable and responsive – she replies with lightning speed and is always there to help, no matter what other pressures she is under. She is a highly knowledgeable and talented advocate.’ Legal 500 2023 (Administrative and Public Law)

• "Arianna is very approachable and easy to work with and gives clear, helpful advice.’ ‘She is very proactive and helpful. She has a good way with clients. She takes a very commercial and pragmatic approach and cuts through issues quickly." Chambers and Partners 2023

• "Arianna has an incredible eye for detail and her passion for the law is evident. She is confident, trustworthy and thorough." Chambers and Partners 2023

• "Arianna is an absolute delight to work with." Chambers and Partners 2023

Cases of note

• Seabrooke Manor Ltd, R (On the Application Of) v Care Quality Commission [2024] EWHC 2203 (Admin) – Acted as junior counsel for the CQC in a public law challenge to findings by the CQC, raising issues regarding findings of fact by the CQC and application of CQC practice guidance and policy.
• R (Bumju Kim) v The Governor of HMP Wandsworth [2024] 645 (Admin) – Acted as sole counsel for the defendant in a habeas corpus challenge brought by a man who was held for more than 24 hours after his release from custody was ordered by a court.
• R(A) v The Lord Chancellor (2024) – Acted as junior counsel for in an Article 14/Article 6 and 8 ECHR discrimination challenge on the basis of age against the Lord Chancellor in the operation of Legal Aid nationally.
• IN -v- St Andrews Healthcare and others [2024] UKUT 411 (AAC) – Acted for the Law Society before the Upper Tribunal in an appeal relating Article 5(4) ECHR rights in the context of to a Tribunal’s decision not to adjourn where a patient refused to attend a hearing and had no legal representative.
• JB v- Elysium Healthcare and Secretary of State for Justice (HM) [2025] UKUT 009 (AAC) Acted for a patient in an appeal to a tribunal decision based on a mistake of fact, and whether medical treatment is ‘available’ if the hospital in which he is detained has the resources to provide it but is not willing to do so.
• R(A&B) v Secretary of State for Health and Social Care - Acted as junior counsel for the Department of Health and Social Care in a high-profile judicial review to the eligibility criteria of a national scheme relating to benefits for children and families.
• R(A Child) v Crown Prosecution Service - Acted as junior counsel on behalf of a child claimant to challenge a decision by the Crow Prosecution Service to charge him with a number of serious offences rather than offer a caution.

Arianna works extensively in issues relating to medical treatment, community care, mental health and inquests. She is a leading junior for Court of Protection (Health and Welfare) and Community Care (Chambers and Partners). Arianna works extensively in healthcare and community care, advising local authorities, NHS bodies, and national public bodies on both policy and individual matters relating to health, social care, and mental health. She frequently undertakes judicial reviews in areas including eligibility and care planning, community care charging, safeguarding investigations, and provider de-registration. She sits as a Family Recorder, First-tier Tribunal Judge (Mental Health), and Court of Protection Judge, and regularly acts and advises in a range of judicial reviews and public law matters concerning the Mental Health Act 1983 and Children Act 1989.

She acts in inquests, focusing on those with issues relating to the Mental Health Act or death of people detained in care settings.

Cases of note

• E & F (Minors: Blood Transfusion) [2021] EWCA Civ 1888 - Junior counsel for a health trust in the Court of Appeal on the leading case on applications in the inherent jurisdiction for the medical treatment of minors.
• Seabrooke Manor Ltd, R (On the Application Of) v Care Quality Commission [2024] EWHC 2203 (Admin) – Acted as junior counsel for the CQC in a public law challenge to findings by the CQC, raising issues regarding findings of fact by the CQC and application of CQC practice guidance and policy.
• Nottinghamshire Healthcare NHS Foundation Trust v MC [2025] EWHC 920 (Fam) Acted on behalf of a patient in a high security psychiatric hospital in a contested application as to whether certain medical treatment fell within the scope of the Mental Health Act 1983.
• Re MK (Deprivation of Liberty and Tier 4 Beds) [2024] EWHC 1553 (Fam) Acted for a mental health trust and NHS England in a case considering the Article 2 and 3 ECHR obligations on acute and mental health trusts to children with high needs arising out mental health conditions and trauma.
• IN -v- St Andrews Healthcare and others [2024] UKUT 411 (AAC) Acted for the Law Society before the Upper Tribunal in an appeal relating Article 5(4) ECHR rights in the context of to a Tribunal’s decision not to adjourn where a patient refused to attend a hearing and had no legal representative.
• JB v- Elysium Healthcare and Secretary of State for Justice (HM) [2025] UKUT 009 (AAC) Acted for a patient in an appeal to a tribunal decision based on a mistake of fact, and whether medical treatment is ‘available’ if the hospital in which he is detained has the resources to provide it but is not willing to do so.
• Guy’s & St Thomas’ NHS Foundation Trust and Royal Borough of Greenwich v M, F, and R [2021] EWHC 2377 (Fam) - Acted on behalf of the child’s guardian in an application to withdraw life-sustaining treatment. Before Mr Justice Cobb.
• Re Z (Medical Treatment: Invasive Ventilation) [2021] EWHC 2613 (Fam) - Acted on behalf of a father of a child contesting an application by a health trust to set a ceiling of care for a child with serious illness, with the child not to be offered invasive ventilation. Before Mr Justice Peel.
• R(KP) v South Tees CCG and NHS England - Acted as sole counsel in a claim challenging the lawfulness of a refusal of NHS Continuing Healthcare, and claims of systemic unfairness in such eligibility decisions.

“Arianna is a brilliant advocate who can pick complex things up very quickly and understand all the nuances.” Chambers and Partners 2025 (Community Care)

“Arianna is very approachable and easy to work with and gives clear, helpful advice.” “She is very proactive and helpful. She has a good way with clients. She takes a very commercial and pragmatic approach and cuts through issues quickly.” Chambers and Partners 2024 (Community Care)

Arianna works extensively in issues relating to community care, mental health and inquests. She is a leading junior for Community Care (Chambers and Partners), Administrative and Public Law (Legal 500) and the Court of Protection (Health and Welfare). Arianna works extensively in healthcare and community care, advising local authorities, NHS bodies, and national public bodies on both policy and individual matters relating to health, social care, and mental health for both children and adults. She frequently undertakes judicial reviews in areas including eligibility and care planning, community care charging, safeguarding investigations, and provider de-registration. She sits as a Family Recorder, First-tier Tribunal Judge (Mental Health), and Court of Protection Judge, and regularly acts and advises in a range of judicial reviews and public law matters concerning the Mental Health Act 1983 and Children Act 1989. She also regularly appears in Mental Health matters relating to patients detained in secure settings, and advises on complex mental health discharge arrangements. She is the author of Social Care Charging, the leading text in this area, and is noted by Legal 500 for her “Outstanding knowledge of the Care Act.”

She acts in inquests, focusing on those with issues relating to the Mental Health Act or death of people detained in care settings.

Cases of note

• J v Bath and North East Somerset Council [2025] EWCA Civ 478 Sole junior counsel to substantively address the Court of Appeal on a leading case relating to the authorisation of deprivations of liberty of children under Article 5 ECHR for children in care.
• Nottinghamshire Healthcare NHS Foundation Trust v MC [2025] EWHC 920 (Fam) Acted on behalf of a patient in a high security psychiatric hospital in a contested application as to whether certain medical treatment fell within the scope of the Mental Health Act 1983.
• R(Seabrooke Manor Ltd) v Care Quality Commission [2024] EWHC 2203 (Admin) Acted as junior counsel for the CQC in a public law challenge to findings by the CQC, raising issues regarding findings of fact by the CQC and application of CQC practice guidance and policy.
• Re MK (Deprivation of Liberty and Tier 4 Beds) [2024] EWHC 1553 (Fam) Acted for a mental health trust and NHS England in a case considering the Article 2 and 3 ECHR obligations on acute and mental health trusts to children with high needs arising out mental health conditions and trauma.
• IN -v- St Andrews Healthcare and others [2024] UKUT 411 (AAC) Acted for the Law Society before the Upper Tribunal in an appeal relating Article 5(4) ECHR rights in the context of to a Tribunal’s decision not to adjourn where a patient refused to attend a hearing and had no legal representative.
• JB v- Elysium Healthcare and Secretary of State for Justice (HM) [2025] UKUT 009 (AAC) Acted for a patient in an appeal to a tribunal decision based on a mistake of fact, and whether medical treatment is ‘available’ if the hospital in which he is detained has the resources to provide it but is not willing to do so.
• R(A&B) v Secretary of State for Health and Social Care - Acted as junior counsel for the Department of Health and Social Care in a high-profile judicial review to the eligibility criteria of a national scheme relating to benefits for children and families.
• R(E) v Telford & Wrekin Council - Acted as junior counsel in an Article 14 challenge to a local adult social care charging policy under the Care Act 2014.

Arianna accepts instructions on inquest matters, particularly those relating to detention under the Mental Capacity Act or Mental Health Act, or deaths in care homes.

Cases of note

• Inquest touching on the death of Janet Scott – Acted for a mental health trust in a four-day inquest for a community mental health patient, in which the coroner was considering findings of neglect.
• Inquest touching on the death of William Stansfield – Acted for a mental health trust in a four-day Article 2 inquest with a jury, relating to a man who had died while detained under the Mental Health Act 1983.
• Inquest touching on the death of Lewis Smedley - Acted for a local authority in a four-day inquest considering the actions of public bodies in relation to a young man who died very shortly after being released from detention under s136 Mental Health Act.
• Inquest touching on the death of Vera Tye - Acted for a local authority in an inquest relating to the death of a woman living in a residential care home operated by the local authority; the inquest also considered the policies and procedures relating to the use of bank staff.
• Inquest touching the death of Duncan Stewart - Acted for a care home provider relating to the death of a man who died following a fall in the care home. 

Arianna is a qualified mediator with a keen interest in the use of mediation in Court of Protection health and welfare and property and affairs contexts.