Dr Sarah McCosker, a Partner and co-founder of Lexbridge, brings over 25 years of esteemed international legal expertise to her practice. Her work primarily focuses on international humanitarian law, international human rights law, and the intricate negotiation of intergovernmental instruments, coupled with a deep understanding of the interplay between international law and diplomacy, particularly with respect to dispute resolution on a global scale. Sarah's advisory role has involved tackling complex and sensitive international law issues, where she has been pivotal in negotiating a variety of international instruments, ranging from treaties to other significant agreements, whilst supporting substantial projects aimed at the domestic application of international obligations. Her extensive legal portfolio encompasses diverse fields, including defence, security, military law, anti-money laundering, and counter-terrorism financing. Beyond her professional endeavours, Sarah is committed to volunteer and pro bono work, training, and capacity-building, while actively engaging in academic research and writing within the sphere of international law scholarship. Called to the Bar in 2002, Sarah's distinguished career includes impactful roles at the International Committee of the Red Cross and engaging positions at the Office of International Law within the Australian Attorney-General's Department. Her academic contributions are noteworthy, having served as a Tutor in International Law at the University of Oxford, alongside roles such as Graduate Teaching Assistant and Assistant Dean at the same institution. Her early career saw her as an Associate to Justice A. Philippides at the Supreme Court of Queensland, further bolstering her robust legal foundation. Sarah's academic credentials are equally impressive, holding a D.Phil in International Law from the University of Oxford, following her Master of Philosophy and Bachelor of Civil Law degrees, also from Oxford. She completed her foundational legal education with a Bachelor of Laws (Hons) from The University of Queensland, where she also earned a Bachelor of Arts (Hons) in English and French.
Partner
Lexbridge
Jan 2015 - Present • 11 years 10 months
Legal Adviser
ICRC
Jan 2013 - Jun 2017 • 4 years 5 months
International Lawyer
Attorney-General's Department · Full-time
Jan 2006 - Jan 2013 • 7 years
Graduate Teaching Assistant in International Law
University of Oxford Law Faculty
Jan 2005 - Jan 2006 • 1 year
Tutor in International Law
Oxford University Foreign Service Programme
Jan 2005 - Jan 2006 • 1 year
Legal Research Assistant
Law Commission of England and Wales
Jan 2004 - Jan 2005 • 1 year
Assistant Dean
Brasenose College, University of Oxford
Jan 2003 - Jan 2006 • 3 years
Associate to Justice A. Philippides
Supreme Court of Queensland · Full-time
Jan 2001 - Jan 2002 • 1 year
International Baccaleaurate
La Chataigneraie, International School of Geneva
D.Phil (PhD)
University of Oxford
2004 - 2008
Master of Philosophy (Law)
University of Oxford
2003 - 2004
Queensland Bar Practice Course
2002
Bachelor of Civil Law (Masters degree)
University of Oxford
2002 - 2003
Bachelor of Arts (Hons)
The University of Queensland
1996 - 1999
Bachelor of Laws (Hons)
The University of Queensland
1996 - 2001
Last checked: 8 Sept 2026 • Checked with ACT Law Society
