The Team

Our founding partners are Andrew Williams, Mark Williams and Marie O’Toole – learn about their skills and experience below, or contact us to speak directly with any of our staff members.

Andrew is the senior founding partner at Williams Barristers and Solicitors. Formerly a criminal Barrister and Solicitor with another Adelaide leading criminal defence firm, he brings a wealth of experience to the practice. Andrew holds a LLB/LP (Hons) from Flinders University of South Australia and has been admitted to Practice in the High Court of Australia, the Supreme Court of South Australia and the High Court of Solomon Islands. He is a member of the Legal Services Commission Complex Criminal Law Panel (Counsel & Solicitor) as well as the Law Society of South Australia.

Andrew has previously worked as a Prosecutor with the Office of the Director of Public Prosecutions, an International Legal Adviser to the Solomon Islands Government assisting Restoration of Law and Justice Processes and Institutions following a civil war, and has 22 years experience as a Police Officer. He has also tutored at Flinders University Law School. Andrew’s breadth of experience means you get the benefit of in-depth legal and investigative knowledge, advocacy and negotiation skills. Andrew has a focus on defending criminal and traffic matters and providing strong representation for each client.

Call Williams Barristers and Solicitors Adelaide on 08 8451 9040 to make an appointment with Andrew.

Mark is a founding partner of Williams Barristers and Solicitors. His principal areas of practice are Criminal Law, Wills and Estates, and Traffic Law. Mark holds a LLB/LP and BIntSt from Flinders University of South Australia and is a member of the Law Society of South Australia and the Legal Services Commission General Panel.

Mark has developed a broad range of skills and knowledge through his work in private firms in Adelaide and through working with the Aboriginal Legal Rights Movement and Office of the Director of Public Prosecutions in the Solomon Islands. Having represented clients in criminal, family and probate matters in South Australia, Western Australia, New South Wales and Queensland, Mark possess a wealth of legal and procedural knowledge.

Mark applies his experience and knowledge to achieve the best possible outcome for his clients whether that be in the Magistrates Court, District Court or Supreme Court.

He is also well versed in the drafting of Wills, Estates, Power of Attorney, and Advance Care Directives and in assisting clients to make applications to the Supreme Court for grant of Probate and Letters of Administration.

With his calm, confident and considered approach, Mark will achieve the best possible result for you and your family while always treating you with dignity and respect.

Call Williams Barristers and Solicitors Adelaide on (08) 8451 9040 to make an appointment with Mark.

Natalia is the head of our Family Law team. With over 10 years in practice, Natalia possesses a wealth of experience having worked on both litigious and non-litigious matters involving complex property and parenting disputes.

Natalia has particular expertise in matters involving rural assets, investments and trusts as well as multi-party disputes involving the Department for Child Protection, grandparents, and proceedings in the Evatt and Magellan lists, Division 1 matters and harmful proceedings orders.

Natalia understands the various needs of clients at times of high conflict and the emotional toll that legal disputes can take. She believes transparency, frank advice and communication are key when it comes to client relationships and strives to deliver the best outcome for clients in a calm and professional manner

Natalia holds a Master of Laws through the University of Adelaide and is fluent in Polish.

Courtney is a dedicated criminal defence lawyer committed to delivering strong, strategic advocacy for every client. She holds a Bachelor of Laws with Honours from the University of South Australia, followed by a Graduate Diploma in Legal Practice completed through the Law Society of South Australia and the University of Adelaide. She is undertaking a Master of Laws with the University of New England, reflecting her ongoing commitment to excellence and continual professional growth.

As a member of the Law Society of South Australia and the Legal Services Commission General Panel, Courtney is trusted to provide high-quality representation across a broad range of criminal matters. She regularly appears in all South Australian courts and has developed extensive experience in both trial and appellate work.

Courtney has acted as instructing solicitor in numerous District Court trials and Supreme Court appeals, working closely with senior counsel on complex and high-stakes matters.

With a calm, thorough and client-focused approach, Courtney is dedicated to achieving the best possible outcome in every case.

Call Williams Barristers and Solicitors Adelaide on (08) 8451 9040 to make an appointment with Courtney.

Stephanie is a dedicated and approachable lawyer at Williams Barristers and Solicitors, practising in the areas of Wills & Estates and Family Law. She was admitted as a barrister and solicitor of the Supreme Court of South Australia in 2025, following her graduation with a Bachelor of Laws and Legal Practice from Flinders University.

Prior to her admission, Stephanie spent four years working in criminal law, where she discovered her passion for working in a client-focused field. She understands all matters are unique and brings compassion, clear communication and professionalism to her practice, helping clients make confident decisions about their future and their families.

Stephanie takes pride in working closely with clients to understand their needs and deliver straightforward and practical advice. She is committed to making the legal process feel less overwhelming for her clients and offers guidance and support as they navigate their way through complex and challenging times. Stephanie values a collaborative approach to resolving matters, however, where litigation is necessary, she is a strong and determined advocate for her clients.

Call Williams Barristers and Solicitors Adelaide on (08) 8451 9040 to make an appointment with Stephanie.

Katherine Gariboli is our friendly and welcoming Senior Administrator.  In a return to the legal industry, she joined the Williams team in 2024. Katherine brings a wealth of experience and expertise gained from her previous work within the legal industry as well as a broader range of businesses and professions. She has always enjoyed working within team environments and assisting clients with their enquiries. 

As the Williams Legal front of house, Katherine continues to utilise her administrative skill set and display he warmth and welcoming nature as you enter our office.

Marie is a founding partner of Williams Barristers and Solicitors.

Marie holds a M Ed, B Ed and Dip T. She brings a range of management expertise to the firm from broad experience in executive positions and educational leadership. As first point of contact in our office, Marie will make sure you are able to quickly access the legal support you need in a friendly and no nonsense manner.