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Declan O'Callaghan

Declan O'Callaghan



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Declan O’Callaghan has a broad public law practice with a strong reputation in judicial review and appellate work. Much of his work has an international law dimension.

Declan is recommended by Legal 500 as being in Tier 1 of leading junior counsel for administrative and public law (one of only three counsel). 

Directory recommendations

What they say:

Public Law

‘Dedicated to each and every one of his cases, no matter how busy he is.’ Legal 500 (2017)
‘Highly experienced senior junior offering a wealth of expertise across diverse areas such as mental health, asylum, unlawful detention, prisoner’s rights and equality law.’ Chambers & Partners (2017)
“Brilliant to work with.” Legal 500 (2016)
“A benchmark for junior barristers in the field.” Legal 500 (2015)
“An accomplished public lawyer, adept in his handling of complex international human rights, asylum and EU free movement cases.” Chambers & Partners (2015)
Possesses “an extraordinary breadth of knowledge.” Legal 500 (2014)
“Brilliant.” Legal 500 (2013)
“Exceptional.” Legal 500 (2012) 

Civil Liberties

‘His written work and skeleton arguments are prepared down to minute detail, he hammers things down completely and that makes him a very attractive advocate.’ Chambers & Partners (2017)
Declan is great. He is dedicated, he is sensible and he doesn’t take bad points.’ Chambers & Partners (2017)
“Highly experienced senior junior offering a wealth of expertise across diverse areas.” Chambers & Partners (2016)
“His renowned practice is international in scope, involving in situ pro bono work as far afield as India and Sri Lanka.”Chambers & Partners (2016)
"He's affable and works wonderfully in a team by keeping things dynamic and organised." Chambers & Partners (2016)


‘Vastly experienced, he has been instructed in significant matters in both domestic and EU courts. He is regularly sought after for his depth of knowledge of Dublin Regulations and EEA rights.’ Chambers & Partners (2017)
‘Extremely knowledgeable on all immigration matters, particularly EEA rights.’ Legal 500 (2017)
“He has a wide spectrum of knowledge that he brings to individual cases.” Legal 500 (2016)
"He continues to lead the pack on cases relating to immigration." Chambers & Partners (2016)
“Vastly experienced.” Chambers & Partners (2016)
"He's brilliant: very to the point, a sterling advocate and his drafting is excellent, he really knows his stuff." Chambers & Partners (2016)
“A brilliant advocate.” Legal 500 (2015)
Very reliable, very easy to approach and particularly good with Article 8 medical cases.” Chambers & Partners (2015)
“Very user-friendly and very good. He’s a good one to go to for the more unusual cases.” Chambers & Partners (2015)
“An immigration specialist with crossover knowledge in matters involving EU law. He is an expert on unlawful detention.” Chambers & Partners (2014)
“Very approachable and knowledgeable.” Legal 500 (2014) 


“He is highly acclaimed for his international work and has significant experience in death penalty work in Africa and South East Asia, in situ pro bono work in Sri Lanka and provision of advice to the Tibetan government-in-exile.” Chambers & Partners (2017) 

Nature of Practice

Declan practices in public law, local government and international law. He is regularly instructed in a wide range of matters including housing, prisons, immigration and asylum, education, social welfare, community care, mental health and regulatory matters. He represents in the Court of Protection. He has a strong interest in European Union law.

He has appeared at all levels of domestic courts from a variety of tribunals to the House of Lords. He has worked extensively in the High Court and the Court of Appeal. He enjoys a wide scope of instructions from private clients, local authorities, NGOs, and charities.

He has represented in matters before the European Court of Human Rights, the Court of Justice and in individual complaints before the United Nations Human Rights Commission.

Declan is a specialist reviewer for the Bar Pro Bono Unit. 


Declan is a Member of the Chartered Institute of Arbitrators (MCIArb).

He is an Associate Member of the Hong Kong Institute of Arbitrators (AHKIArb). 

He undertakes both domestic and international arbitration. 

Administrative and Public Law 

Declan practices in all areas of public law and appears at all levels of domestic courts, particularly the Administrative Court and the Court of Appeal. He regularly advises in matters involving human rights and European Union law.

Declan is regularly instructed in local government matters concerning housing and homelessness, education and community care. He regularly advises on matters of procedure including matters of equality and confidentiality. He has a particular interest in mental health and disability issues and has regularly advised in matters concerning the duty of local authorities in respect of social services provision.

For more detail including recent cases please click here. 

Prison Law 

Declan has established a strong reputation in the field of prison law and the Legal 500 (2010) confirmed that Declan “is expert in Parole Board representation”. For more detail including recent cases please click here. 


Declan has a strong interest in international law. He has lectured on human rights and international issues in a number of countries. For more detail including recent cases please click here. 

Death Penalty Work 

Since 2014, Declan has acted as Amicus Curiae in the “Kigula beneficiaries” matters before the Ugandan High Court and Court of Appeal. In all matters he leads Ms. Tanya Murshed (1 MCB). 

The hearings concern the re-sentencing of some 600 persons convicted of capital crime offences following the replacement of the mandatory death penalty with a discretionary death penalty. 

In 2016 he acted as Amicus Curiae in over 20 appeals before the Ugandan Court of Appeal. 

He has also acted as Amicus Curiae in death penalty matters arising from court-martials. 

He has undertaken advisory work in prisons in Africa including work with death row prisoners in Luzira prison, Kampala, on several occasions. 

He has presented seminars upon death penalty mitigation to the judiciary, lawyers and military in Uganda (2011, 2013, 2014 and 2016) and Malawi (2011). 

He presented a seminar to Supreme Court justices in Malawi on mitigation and sentencing in death penalty matters (2011). 


Declan is a patron of the Hackney Community Law Centre. 

He regularly works on behalf of The Centre for Capital Punishment Studies (London), Democratic Progress Institute (London) and Evolve – Foundation for International Legal Assistance (London and Kampala, Uganda).


Barrister member of Bar Tribunals and Adjudication Service.

View Declan's profile on our International site