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Administrative & Public Law
Criminal Law
Employment Law
Family Law
Human Rights
Inquests / Royal Commissions / Statutory Tribunals
Medical Negligence
Public International Law
Sports Law


Admitted as a Solicitor 2006 (NSW)
Admitted as a Barrister 2017 (NSW)
Also admitted in Northern Territory and South Australia


Sebastian commenced his legal career working as a Tipstaff to a Supreme Court justice. After a decade working as a solicitor, including running his own law firm in the Sydney CBD, Sebastian was admitted as a barrister in 2017.

As a criminal lawyer, Sebastian regularly appears before juries as well as judge alone matters, particularly in the District Court (with favourable results for his clients). While he typically acts as a criminal defence lawyer, he has also prosecuted matters including white collar prosecutions for the Australian Securities Investment Commission (ASIC) and those involving doctors accused of Medicare fraud.

Sebastian has a broad practice and regularly accepts briefs in the areas of Employment Law, Family Law, Inquests and Commissions of Inquiry, Administrative, Public and Human Rights including Migration Law.

Outside of legal practice, Sebastian has been a Practitioner in Residence at the Australian Research Council’s Centre for Excellence in Policing and Security (CEPS) and has been a sessional lecturer in both the law school and criminology faculty of Western Sydney University, as well as the Australian Catholic University’s Thomas More Law School. He has been a member of the Criminal Law Committee of the Law Society of NSW (2010-2016), the Human Rights Committee of the Law Society of NSW (2009, 2016) and the Human Rights Committee of the NSW Bar Association (2018-2019).

Sebastian holds degrees in business and law (with First Class Honours), and a Masters of Law from the University of Cambridge (where he was David M. Livingstone Scholar and recipient of a Pegasus Award).

Recent Criminal AppealsKramer v R; R v Kramer [2023] NSWCCA 152 (led by Stratton SC) – successfully held Community Corrections Order for charge of sexual intercourse without consent.

Application by Maksimilian Bebic, Mile Nekic and Vjekoslav Brajkovic pursuant to s 78 of the Crimes (Appeal and Review) Act 2001 (NSW) [2022] NSWSC 1153 (unled) (‘the Croatian Six case’) where Wright J ordered an inquiry into the convictions of the Croatian Six after 41 years.

Application by Crespin Adanguidi pursuant to s 78 Crimes (Appeal and Review) Act 2001 (NSW) [2022] NSWSC 442 (unled) – triple homicide convictions spanning back to 2005 – where Dhanji J found a doubt or question as to guilt and referred the matter to the NSW Court of Criminal Appeal.

Employment LawWoods v Industrial Relations Secretary on behalf of the Office of the Director of Public Prosecutions [2021] NSWIRComm 1054.

State of South Australia v Collins [2018] SASCFC 110 (led by Brian Hayes QC) – matter referred to Full Court of South Australia due to a matter of public importance – Crown appeal successfully resisted.

Family LawNaidu & Seth [2021] FedCFamC2F 229.

Human rightsAustralian Human Rights Commission proceedings – lawyer for Connor McLeod and Vision Australia in their discrimination complaint against the Reserve Bank of Australia (RBA) for failing to incorporate tactile features on Australian banknotes (despite the RBA already making such banknotes for various Asia-Pacific countries). Following the complaint and tireless campaigning by Mr McLeod and his family, the RBA announced the release of new series of new generation banknotes/Australian currency incorporating tactile markings for the blind and visually impaired.

Inquests and InquiriesSebastian has a longstanding interest in inquests and inquiries. As a solicitor, he was involved in a number of high-profile matters including: Operation Prospect; The Inquest into the death of Roberto Laudisio Curti (death after the use of tasers), and the Inquest into the deaths of James Thomas Martin, Robert Hugh Frederick Poate, Stjepan Rick Milosevic (Soldiers’ death in Afghanistan Inquest). More recently, as counsel, Sebastian has been briefed in a variety of coronial proceedings including the Inquest into the death of Tristan Naudi; Inquest into the death of SP; Inquest into the death of Darren Higgins; Inquest into the death of Lachlan Cairns; Inquest into the death of Todd McKenzie; Inquest into the death of Michael Murray; Inquest into the death of Malcolm Small; Inquest into the death of Jai Wright and the Inquest into the death of FS. He is currently briefed by the petitioners in the Croatian Six Inquiry, looking into the convictions of those men for terrorism offences some 43 years after their original trial.

RECENT PUBLICATIONSDe Brennan S. Dancing away from Reform: The Inquest into the Death of Six Patrons of NSW Music Festivals. Journal of Law & Medicine 2020 Apr 27(3):693-706.

De Brennan, S. ‘Reviewing the reviewers: EPAC and the 2019 Tedeschi Report’ Education Review, September 17, 2019.

De Brennan, S. ‘Freezing notices and confiscation powers: New punitive roles for police?’ (2011) Criminal Law Journal, Volume 35, p. 345-360.

De Brennan, S. ‘A Tainted Act? Exploring the human rights implications of Asset Confiscation Legislation’ Seminar at Australian Research Council Centre of Excellence in Policing and Security (CEPS), 18 November 2010.

Contributing editor, Legal Secretary’s Handbook 9th Edition (2010), Law Society of NSW (chapter on Litigation and Criminal Law).

De Brennan, S. ‘Geoffrey Robertson, The Statute of Liberty – How Australians can take back their rights (2009)’ Australian Journal of Human Rights: 213: 221.

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