In Australia, when we say 'criminal law' we mean two different things: the substantive criminal laws and the procedural criminal laws.
Substantive criminal laws are those laws passed by the state legislatures or the federal legislature that define certain acts and behaviours as crimes and provide penalties for them.
Procedural laws are those laws passed by the state legislatures or the federal legislature that set the rules for the orderly and just prosecution of crimes.
Procedural laws involve the police or law enforcement agencies, the prosecution service, the courts that try the crimes, and prisons where penalties are served.
When we say that a ‘crime’ has been committed, it means that a person or persons have committed certain acts and behaviour that has been defined by law as punishable ; either because the acts and behaviour are wrong in itself or, they are wrong given a particular set of factual circumstances.
For instance, shooting and killing a soldier in the army against whom Australia has declared war may not be a crime, but the shooting and killing of one’s spouse may be a crime. In this instance, the law has defined as ‘unlawful’ the shooting and killing of one’s own husband; whereas, there is no law punishing a soldier in the army for shooting and killing another soldier from the opposing army.
Crimes are not only defined by law and statute but also by common law. When we say ‘common law’ we refer to ‘judge-made laws’ that is, we refer to specific decisions of courts that define certain acts and omissions as crimes. The common law (or the law as applied by the courts in specific cases) can also provide legal defenses.
Legal defenses are those factual circumstances which when present can mitigate or negate criminal liability. For instance, shooting and killing one’s own husband may be a crime, but if the husband was shot and killed by his wife while the husband was beating his wife, then, the facts give the wife a legal defense that can mitigate or negate criminal liability. She shot and killed her husband in defense of herself.
Thus, acts and omissions become ‘crimes’ when they are defined as such in a law or in a decision made by a duly constituted court. Certain acts and omissions become crimes because they are treated as crimes by the police, the prosecutors, the courts and the prisons in accordance with law.
Disclaimer : This article is just a summary of the subject matter being discussed and should not be regarded as a comprehensive legal advice for you to defend yourself alone. If you are charged with criminal offences, it is recommended that you seek legal assistance from criminal lawyers.