Marwan Osseiran
Marwan Osseiran
Principal Lawyer
Marwan is a highly respected and seasoned trial lawyer, advocating for his clients both inside and outside the courtroom.
He has a distinctive standing and is uniquely positioned to serve a culturally and linguistically diverse clientele across North America, the United Kingdom, the Middle East, and beyond, a capability that sets him apart from other practitioners.
Marwan has built a reputation as a leading criminal and civil litigation lawyer experienced in handling a wide variety of matters in federal, criminal and civil court for individual and corporate clients. In addition to his practice in Canada, Marwan is active before international criminal tribunals, including the International Criminal Court and the Special Tribunal for Lebanon in The Hague.
Since 2020, he has received several appointments from the United Nations' Office of the Ombudsperson on the Sanctions Committee, as Legal Representative for petitioners seeking to delist. He is a recognized counsel in in Ottawa and Toronto in the criminal bar for litigating difficult and complex cases in both French and English. He uses his courtroom and advocacy skills equally before the international tribunals.
Qualifications & Admissions
Qualifications & Admissions
Barrister, The Honourable Society of Middle Temple, Bar of England & Wales
(called 2021)Barrister, The Honourable Society of Lincoln's Inn, (Ad Endum 2022)
Barrister & Solicitor, Law Society of Ontario, Canada (2008)
Admitted Counsel, International Criminal Court (Victims & Suspects),
The Hague (2018)Admitted Counsel, Kosovo Specialist Tribunal, The Hague (2019)
Legal Representative for Victims, Special Tribunal for Lebanon (2019)
Former Visiting Professional, ICC Registry, International Criminal Court
(2018–2019)Lists of Counsels- Legal Representatives for petitioners before the United Nations
Sanctions Committee (2020)
Barrister, The Honourable Society of Middle Temple, Bar of England & Wales (called 2021)
Barrister, The Honourable Society of Lincoln's Inn, (Ad Endum 2022)
Barrister & Solicitor, Law Society of Ontario, Canada (2008)
Admitted Counsel, International Criminal Court (Victims & Suspects), The Hague (2018)
Admitted Counsel, Kosovo Specialist Tribunal, The Hague (2019)
Legal Representative for Victims, Special Tribunal for Lebanon (2019)
Former Visiting Professional, ICC Registry, International Criminal Court (2018–2019)
Lists of Counsels- Legal Representatives for petitioners before the United Nations Sanctions Committee (2020)
Education
Education
Licence en droit, Beirut, London
LL.M. in American Laws, Boston University School of Law
LL.M. (International Trade & Competition Law), McGill University —
Graduate Comparative Law InstituteLL.B. The Federation of the Law Societies of Canada - National Committe on
Accreditation for Foreign Trained LawyersAdvanced Studies in International Criminal Law, International Dispute Settlement
& Arbitration, Leiden University, The Hague
Barrister, The Honourable Society of Middle Temple, Bar of England & Wales (called 2021)
Barrister, The Honourable Society of Lincoln's Inn, (Ad Endum 2022)
Barrister & Solicitor, Law Society of Ontario, Canada (2008)
Admitted Counsel, International Criminal Court (Victims & Suspects), The Hague (2018)
Admitted Counsel, Kosovo Specialist Tribunal, The Hague (2019)
Legal Representative for Victims, Special Tribunal for Lebanon (2019)
Former Visiting Professional, ICC Registry, International Criminal Court (2018–2019)
Lists of Counsels- Legal Representatives for petitioners before the United Nations Sanctions Committee (2020)
Sarah J. Shlymon
Sarah J. Shlymon
Legal Assistant
Sarah is a licensed paralegal with the Law Society of Ontario and an alumna of the University of Toronto. A graduate of Seneca Polytechnic’s accelerated paralegal program, she brings disciplined legal training and regulatory accountability to her practice.
Recognized for her clarity of thought and measured approach, Sarah maintains a client-centered focus grounded in careful analysis and thorough preparation. She is committed to delivering practical, strategic legal solutions within her authorized scope of practice.
Working closely alongside Marwan, Sarah provides hands-on, results-oriented legal support, combining analytical precision with creative advocacy. Her work reflects the firm’s commitment to resilience, responsiveness, and principled representation in every matter.