A prosecution is a criminal charge against a person. In Victoria, the majority of prosecutions are brought by the Director of Public Prosecutions (DPP) under the Public Prosecutions Act 1994 (Vic), who brings proceedings on behalf of the public as a whole. However, it is possible for individual members of the public to initiate some prosecutions themselves. If a person other than the DPP does decide to initiate a prosecution, it is called a 'private prosecution'.

In Victoria, two types of offence exist: indictable and summary. Indictable offences are more serious offences and must be tried before a judge and jury. Only the DPP and Crown Prosecutors, who are lawyers who work exclusively for the DPP, are entitled to prosecute for indictable offences. Summary offences are generally less serious offences than indictable offences and may be heard before a magistrate sitting alone. Individuals may prosecute any summary offence 'of a public nature', unless the right to prosecute has been excluded.

There is little case law on when an offence will be 'of a public nature'. There is older case law that suggests that what would now be considered to be an environmental offence will probably be an offence 'of a public nature'.

In Armstrong v Hammond [1958] VR 479, Chief Justice Herring and Justices O'Bryan, Dean, Sholl and Adams ruled that the offence of wilfully damaging property was an offence of a public character, at least where the property was public property. In that case, the accused had hired men to try and chop down trees on the foreshore at Rosebud.

In Lynch v Sloan [1959] VR 656, Chief Justice Herring ruled that the Game Act 1928 (Vic) was an Act for the benefit of the public and so offences under that Act were offences of a public nature.

Even if a summary offence is 'of a public nature', the law may prevent a person from bringing a private prosecution. Sometimes, legislation makes it clear that ordinary people cannot bring prosecutions for particular offences:

(Although note that s 48A of the Environment Protection Act provides an express exception to s 59(2) in respect of the offence of emitting unreasonable noises. See Residential Noise).

In other cases, whether the right to prosecute has been excluded will be a matter of interpretation. For example, in Duncan v Demir [2009] VSC 37, s 77 of the Road Safety Act 1986 (Vic) provided a detailed scheme for who could prosecute offences under the Act and in what circumstances. As such, even though the Act did not say that private individuals could not prosecute under the Act, Justice Kyrou ruled that the right to bring a private prosecution under the Act was implicitly excluded.

In other cases (such as Armstrong v Hammond above), the existence in an Act of a list of people authorised to bring prosecutions under that Act has been held not to exclude the right of people not mentioned in that list to be bring prosecutions.

There are a number of limitations on private prosecutions that make them less attractive than they may at first appear.

1. The prosecutor is required to prove their allegations 'beyond reasonable doubt'. This is a high standard and will often be difficult to meet, particularly as a private prosecutor does not have the same powers as the police to investigate offences.
2. If the prosecution is unsuccessful, the court may award costs against the prosecutor. The costs of a prosecution may be high, particularly where the defendant is a government entity or major corporation.
3. Under the Public Prosecutions Act, the DPP is empowered to take over private prosecutions and discontinue them. The decision to discontinue a prosecution cannot be reviewed.