High Court clarifies law on conspiracy to commit misconduct in public office

The High Court of Australia recently delivered a unanimous judgment in Obeid v The King [2026] HCA 1, concluding one of Australia's most prominent corruption prosecutions. The decision provides crucial clarity on the elements of conspiracy to commit misconduct in public office.

Background to the Obeid case

Edward Moses Obeid, his son Moses Edward Obeid, and former NSW Minister Ian Michael Macdonald were convicted of conspiracy to commit misconduct in public office. The Crown alleged Macdonald misused ministerial powers to grant a coal exploration licence over Obeid family land for an improper financial benefit, estimated at $30 million.

After their convictions were upheld by the NSW Supreme Court and Court of Criminal Appeal, the appellants challenged them in the High Court. They argued the indictment was defective for not specifying the particular unlawful acts agreed upon by the conspirators to constitute misconduct in public office.

Elements of misconduct in public office and conspiracy

The Court adopted the formulation outlined by Sir Anthony Mason, sitting as a non-permanent judge of the Hong Kong Court of Final Appeal in Sin Kam Wah v HKSAR, later developed by Australian intermediate appellate courts.

Under this approach, the offence is established when:

1. the accused is a public official;

2. the conduct occurs in the course of or is connected to their public office;

3. the official wilfully misconducts themselves, whether by act or omission, including wilfully neglecting or failing to perform a duty;

4. the misconduct lacks reasonable cause or justification; and

5. the misconduct is sufficiently serious to warrant criminal punishment, considering the officeholder's responsibilities, the significance of the public objectives served, and the extent of the departure from those objectives.

The High Court’s decision: what is a conspiracy to commit misconduct in public office?

The High Court focused on a core question of criminal law: whether the Crown’s allegation – that the conspirators agreed Macdonald would wilfully misconduct himself in public office regarding the licence grant – legally constituted a conspiracy to commit that common-law offence.

In a unanimous judgment, the Court held:

• The specific agreement alleged by the Crown at trial fully constituted the offence of conspiracy to commit misconduct in public office.

• Prosecutors do not need to allege specific overt acts of misconduct in the indictment; an agreement to undertake acts that collectively satisfy the elements of the predicate offence is sufficient.

• Macdonald’s decision-making, improperly influenced to benefit the Obeids' private interests over the public interest, was correctly characterised as misconduct in public office when viewed with the conspiratorial agreement.

In essence, the High Court affirmed that an indictment for conspiracy to commit misconduct in public office does not require specific articulation of unlawful acts, provided the overall scope of the agreement fulfills the elements of the substantive offence.

Key practical implications

This decision reinforces high-level principles regarding common-law conspiracy offences and their relationship with predicate offences:

• Prosecutors pursuing conspiracy to commit common-law misconduct can rely on an agreement contemplating a course of conduct amounting to the substantive offence, without needing to explicitly detail each overt act.

• The High Court’s reasoning acknowledges the practical challenges prosecutors face in particularising every aspect of unlawful conduct in complex corruption schemes at the indictment stage, while preserving the core elements of conspiracy.

• For defence practitioners, this decision underscores the critical importance of engaging early and robustly with how Crown particulars frame agreements, assessing whether the aggregate agreed conduct legally supports the intended predicate offence.

Broader implications: Corruption and public confidence

The Obeid matter highlights key themes in Australia's approach to corruption litigation and public sector accountability:

• The enduring reach of common law in prosecuting public sector corruption, particularly where statutory frameworks may lack adequate or clear offence pathways.

• The complex interplay between prosecutorial strategy, indictment drafting and appellate review in high-stakes matters involving political actors and significant economic interests.

While largely affirming prosecutorial latitude in framing conspiracy charges, the High Court's decision also underscores that legal precision in indictments, particulars and evidence remains paramount in complex corruption prosecutions.