Ari Katsoulas
Barrister
Ari was called to the Bar in 2014 and specialises in Estates, Equity and Commercial disputes and litigation. He is a recognised expert in Succession Law and family provision claims and has been named in the Doyles Guide as a leading New South Wales Wills & Estates Litigation Junior Counsel.
Ari specialises in commercial, equity and estate litigation, with particular expertise in family provision claims, trust disputes, and contested probate. He is regularly briefed to advise and appear in matters involving testamentary capacity, undue influence, informal wills, and equitable claims such as proprietary and promissory estoppel.
In addition to his substantial estates practice, Ari is frequently retained in a variety of commercial and civil litigation. He is experienced in fiduciary duty breaches (including directors, trustees and executors), misleading and deceptive conduct claims, shareholder oppression claims, corporate and personal insolvency, and real property matters.
Recognised by Doyle’s Guide as a leading wills & estates litigation barrister in New South Wales, Ari has over a decade of experience at the Bar. He is known for his strategic judgment, clear advocacy, and ability to resolve intricate disputes with practical, outcome-focused advice.
Ari is also briefed in estate litigation in the Australian Capital Territory and Queensland, and has been an interstate member of the Queensland Bar Association since 2022. He regularly attends mediations outside of Sydney including in Northern New South Wales, Canberra, Brisbane and the Gold Coast.
Prior to being called to the Bar, Ari worked in the Private Clients (Tax & Legal) team at PWC Australia, providing expert advice to private companies, family offices and High Net Worth Individuals.
Ari is presently a member of the NSW Bar Association Succession & Protective Law Committee. He was previously a member of the NSW Bar Association Diversity and Equality Committee.
Select Cases
Published judgments include:
Appeared for the successful respondents before the Court of Appeal on the proper construction of a will. The decision considered hotchpot clauses, the doctrine of hotchpot, and consequences of admissions made at hearing by counsel. Mr Katsoulas also appeared for the successful defendants at first instance in Estate of Tanner [2025] NSWSC 1078.
Appeared for the successful plaintiff in a family provision claim
Applicable law and choice of law in multijurisdiction probate dispute -testamentary capacity - German Law
Appeared for the successful executors in a will construction case. Mr Katsoulas also appeared for the successful executors in the Court of Appeal in Tanner v Tanner [2026] NSWCA 100
Payment from a fund - UCPR r 42.20 – UCPR 42.25
Family provision claim by adult child against property designated notional estate - acted for the estate.
Appeared for the successful plaintiff in a family provision claim - dispute as to eligibility (de facto)
Appeared for the plaintiff in a family provision claim (adult child) - consideration of "special circumstances" for out of time notional estate claims
Appeared for the successful Defendants resisting a claim in proprietary estoppel - promise to buy a house
Appeared for 5 successful plaintiffs (and one unsuccessful) in a misleading and deceptive conduct claim based on oral representations in connection with a large residential apartment development – judgment of approximately $3,000,000. (And appeared as junior counsel for the successful Respondents on appeal in Lin v Zheng [2023] NSWCA 174)
Appeared for the successful respondent on an appeal concerning knowing assistance of breach of director duties and fiduciary duties
Appeared for the (initially unsuccessful) plaintiffs in a building and construction case - estoppel in commercial contracts. The first instance decision was overturned on appeal in favour of his clients ([2022] NSWCA 269) and special leave refused by the High Court of Australia ([2023] HCATrans 102)
Appeared for the successful Defendant resisting a claim against her for approximately $35million arising from knowing assistance to a breach of director duties/fiduciary duties as part of a dishonest and fraudulent design.
Appeared for the successful plaintiff in winding up application
Appeared for the successful plaintiff - application for possession of human reproductive tissue and ancillary orders.
Admissibility of transcripts obtained of compulsory ATO interviews pursuant to s 353-10 of the Taxation Administration Act 1953 (Cth).
Resisting application for security for costs where it is alleged that the Plaintiff’s impecuniosity resulted from the breach of duty and misappropriation of the defendants.
Summons by Mortgagee to remove caveat – prima facie priority dispute.
Proceedings concerning personal property rights in human tissue.
Application to Set Aside Default Judgment after final hearing of substantive matter against other defendants.
Interest under the Insurance Contracts Act 1984 (Cth).
Payment of Funds out of Court to Equitable Mortgagee/Chargee.
Security for Costs.
The leading authority in New South Wales on Personal Property Rights in Human Tissue and Gametes.
Appeared for the successful Respondent in the New South Wales Court of Appeal – a leading authority on “dependency” in family provision claims.
Declarations of Trust – Replacement of Trustees
Acted for the independent Administrator.
Summary judgment application
Urgent Relief -Personal Property Rights in Human Tissue.
Appointment of Provisional Liquidator in Shareholder Oppression Case.
Security for Costs.
Acted for the successful defendant in proceedings to set aside a Statutory Demand.
Redemption of Mortgage.
Cross vesting Application from Supreme Court to Family Court.
Proprietary Estoppel and Encroachment of Building Act.
Admissions
- Admitted to the Bar (New South Wales) in 2014.
Professional Memberships
- Member, New South Wales Bar Association
- Member, NSW Bar Association Succession and Protective Law Committee
- Member, Commercial Law Association of Australia
- Member, Bar Association of Queensland
- JADE Expert Panel, Consumer Protection Law
Qualifications
- Bachelor of Arts, Macquarie University
- Bachelor of Laws, Macquarie University
Speaking Engagements
- Where the Will does not Carry out the Testator’s Intentions: Rectification of Wills and Testamentary Documents – Two Wentworth Succession Conference March 2025
- Preparing and Defending Family Provision Claims: A Practical Guide for Practitioners – Two Wentworth Succession Conference March 2024
- The eligibility of de facto partners in family provision claims with Irma Remic and Ari Katsoulas – BenchTV, 2024
- Contentious Probate Proceedings & The Role of the Will Drafting Solicitor: Testamentary Capacity – Paper Delivered at the Succession Law Conference: March 2023
- Probate Disputes: Testamentary Capacity, Knowledge and Approval and Undue Influence Paper delivered at the Langham Legal Seminar: November 2021
- Director Duties in Statute and Equity: Recent Cases Paper delivered at the Langham Legal Seminar: November 2021
- Posthumous Extraction of Sperm Cells and IVF: Chapman v South Eastern Sydney Local Health District [2018] NSWSC 1231 – BenchTV, 2020
- Factors Warranting and Shared Households in Family Provision Claims – Paper delivered at the 2 Wentworth Personal Injury and Equity Seminar on 21 March 2016
- Family Provision Claims in New South Wales: An Overview Paper delivered to the Langham Legal Seminar: June 2015
- Preliminary Discovery for Online Piracy: Dallas Buyers Club LLC v iiNet Limited [2015] FCA 317 (2015) Paper delivered to the Langham Legal Seminar: April 2015
- Additional Damages for Infringement – Section 126(2) of the Trade Marks Act 1995 (Cth) Paper delivered to the Langham Legal Seminar: June 2015
- Discrimination, Harassment and Professional Responsibility Paper delivered at The Tilbury Group Legal Seminar, 2015 – 2019.
- Ari also publishes legal articles, posts and CPDs at his website.
