Justice Gleeson was educated at Monte Sant’Angelo Mercy College where she excelled at debating and public speaking, and the University of Sydney from which she graduated with a Bachelor of Arts in 1986, a Bachelor of Laws in 1989 and a Master of Laws in 2005.  Her Honour was admitted as a Solicitor of the Supreme Court of New South Wales in 1989, first working as an associate to Justice Trevor Morling of the Federal Court before joining the firm of Bush Burke & Co.

In 1991, her Honour was called to the Bar of New South Wales, aged only 25. She quickly developed a reputation among eminent leading counsel as a diligent junior gifted with a mastery of detail. Nine years after joining the Bar, her Honour was briefed to appear at the Australian Broadcasting Authority’s “Cash for Comment” inquiry which led to her being offered the position of General Counsel to the Authority.

From the ABA, her Honour moved to the Australian Government Solicitor in 2003, acting for various regulatory authorities and demonstrating a talent and instinct for public and administrative law.

Returning to the Sydney Bar in 2007, her Honour practised in administrative law, competition and consumer law, professional liability, disciplinary proceedings and taxation, taking briefs in a number of significant matters including the Canberra Bushfires case and the Royal Commission into Institutional Responses to Child Sexual Abuse, where she appeared as counsel for the New South Wales Government.  She also served on the Bar Council and committees.

Her Honour was appointed Senior Counsel in 2012, one of 26 appointments that year.  Twelve of these were women; seven of that number, including Gleeson J, became judges in the years that followed. In 2014 her Honour became a judge of the Federal Court at the earnest behest of Allsop CJ, her leader and mentor during her time as a junior barrister.

Speaking at her swearing-in as a Justice of the High Court, Gleeson J paid tribute to her predecessor Justice Virginia Bell, whom she described as “the model of judicial courtesy, tolerance and respect for the individual litigant.  Further, any interested citizen could read and understand her Honour’s judgments without difficulty”, something which Gleeson J observed was “not only an aspect of the rule of law but also crucial for effective democratic participation.”  Of Gleeson CJ, her Honour observed (to audible laughter) that “[t]he opportunity to overrule the decisions of one’s father is rare indeed.  For her part, my mother can still consider her decisions unreviewable”. 

In concluding, her Honour said:

I will allow my father to have the last word concerning the weight of responsibilities that I have taken today.  That weight is heavy.  But “a sense of inadequacy is no excuse for lack of courage or determination.”

Justice Gleeson’s first published appellate judgment in the High Court, with which all six other members of the court agreed, can be found in Namoa v The Queen [2021] HCA 13; (2021) 95 ALJR 396, delivered on 14 April 2021. This judgment can be viewed on New Westlaw (Australia) or Westlaw AU.