Published by Geoff Harrison | 7 October 2023
Conspiracy is a common law inchoate offence, that is, the offence is taking a step towards the principal offence. A conspiracy is an agreement between two or more persons to commit a crime or an unlawful act or a lawful act by unlawful means. The mens rea or intent for the offence is the intention to carry out the agreement. The offence is complete once the agreement is formed. See: Macdonald, Ian v R; Edward Obeid v R; Moses Obeid v R, per Bell CJ, Basten AJA, Button J at .
The history of the offence of Conspiracy is set out by French CJ in R v Lk at , essentially the origins of the offence arose from persons who conspired to make false allegations against others. Proof of the conspiracy or agreement is through the commission of overt acts or acts undertaken in furtherance of the agreement. Further, the co-conspirators rule also applies in that any admission made by a conspirator or co-accused in furtherance of the offence is also admissible against any other co-accused: see Ahern v R at  -  and s87(1)(c) of the Evidence Act 1995.
The sentence for conspiracy given that it is a common law offence is at large. However, where the conspiracy offence relates to a specific statutory offence, the maximum penalty of the statutory offence is used as a yardstick: Vella v R at . Another significant factor in sentencing for Conspiracy is the role to be played by the offender in the offence.
CRIMES ACT 1900 - SECT 26
Conspiring to commit murder
conspires and agrees to murder any person, whether a subject of Her Majesty or not, and whether within the Queen's dominions or not, or
solicits, encourages, persuades, or endeavours to persuade, or proposes to, any person to commit any such murder,
shall be liable to imprisonment for 25 years.
CRIMES ACT 1900 - SECT 342
Certain conspiracy offences not affected
The abolition of the common law offence of conspiring to pervert the course of justice does not prevent a prosecution for an offence of conspiring to commit an offence against this Part.
CRIMES ACT 1900 - SECT 580D
Abolition of rule that husband and wife cannot be guilty of conspiracy
Any common law rule that a husband and wife cannot be found guilty of conspiracy together is abolished.
EVIDENCE ACT 1995 - SECT 87
Admissions made with authority
(1) For the purpose of determining whether a previous representation made by a person is also taken to be an admission by a party, the court is to admit the representation if it is reasonably open to find that--
(a) when the representation was made, the person had authority to make statements on behalf of the party in relation to the matter with respect to which the representation was made, or
(b) when the representation was made, the person was an employee of the party, or had authority otherwise to act for the party, and the representation related to a matter within the scope of the person's employment or authority, or
(c) the representation was made by the person in furtherance of a common purpose (whether lawful or not) that the person had with the party or one or more persons including the party.
(2) For the purposes of this section, the hearsay rule does not apply to a previous representation made by a person that tends to prove--
(a) that the person had authority to make statements on behalf of another person in relation to a matter, or
(b) that the person was an employee of another person or had authority otherwise to act for another person, or
(c) the scope of the person's employment or authority.