A common law principle

10.10  There is a common law principle that presumes ‘mens rea, an evil intention, or a knowledge of the wrongfulness of the act, is an essential ingredient in every offence’.^[1] The general requirement of mens rea is said to be ‘one of the most fundamental protections in criminal law’,^[2] and it reflects the idea that

it is generally neither fair, nor useful, to subject people to criminal punishment for unintended actions or unforeseen consequences unless these resulted from an unjustified risk (ie recklessness).^[3]

10.11  Professors Andrew Ashworth and Jeremy Horder commented that:

The essence of the principle of mens rea is that criminal liability should be imposed only on persons who are sufficiently aware of what they are doing, and of the consequences it may have, that they can fairly be said to have chosen the behaviour and consequences.^[4]

10.12  In He Kaw Teh v The Queen,Brennan J explained the operation of mens rea as an element in criminal offences:

It is implied as an element of the offence that, at the time when the person who commits the actus reus does the physical act involved, he either—

(a)     knows the circumstances which make the doing of that act an offence; or

(b)     does not believe honestly and on reasonable grounds that the circumstances which are attendant on the doing of that act are such as to make the doing of that act innocent.^[5]

10.13  Historically, criminal liability at common law necessarily involved proof of mens rea.^[6] In Williamson v Norris, Lord Russell CJ said the ‘general rule of the English law is, that no crime can be committed unless there is mens rea’.^[7]

10.14  In his Commentaries on the Laws of England, William Blackstone wrote that, to ‘constitute a crime against human laws, there must be first a vitious will, and secondly, an unlawful act consequent upon such vitious will’.^[8]

10.15  Criminal offences are generally characterised in one of three ways:

• mens rea offences—the prosecution must prove a physical element (actus reus) and a mental element (mens rea);

• strict liability offences^[9]—the prosecution is not required to prove mens rea, but there is a defence of reasonable mistake available;^[10] and

• absolute liability offences—proof of mens rea is not required and the defence of reasonable mistake is not available.^[11] 

10.16  In the mid to late 19th century, strict and absolute liability offences were increasingly created by statute, particularly so-called ‘regulatory offences’.^[12] Regulatory offences were designed to protect individuals from the risks that came with greater industrialisation and mass consumerism.

10.17  In Australia, the common law presumes that mens rea is an essential ingredient of a criminal offence is reflected in statute. Chapter 2 of of the Criminal Code codifies the general principles of criminal responsibility which apply to all Commonwealth offences. Offences are made up of physical elements (actus reus at common law) and fault elements (mens rea at common law).^[13]

10.18  A law may expressly provide that there is no fault element for one or more physical elements of an offence. If an offence is designated as a strict or absolute liability offence, no fault elements apply to all of the physical elements of the offence.^[14] If strict or absolute liability is designated to apply to a physical element of an offence, no fault elements apply to that physical element.^[15] A defence of an honest and reasonable mistake of fact applies only in relation to strict liability offences.^[16]  Different fault elements may apply to different physical elements of an offence.^[17]

10.19  Where an offence is silent on the fault element that applies to one or more physical elements of the offence, s 5.6 operates to impose a default fault element. If the physical element relates to conduct, the prosecution must prove intention in relation to that conduct (that is, that the conduct was intended).^[18] If the physical element relates to a circumstance or result, the prosecution must prove recklessness in relation to that circumstance or result.^[19]

10.20  A number of Commonwealth laws expressly impose strict or absolute liability on some physical elements of an offence.^[20] Most commonly, these relate to technical^[21] or jurisdictional^[22] elements, and as such don’t offend the common law principle. However, problems arise when strict or absolute liability applies to physical elements that would normally require fault to render them culpable.^[23] Professor Jeremy Gans submitted:

Some physical elements of a criminal offence almost never lack subjective intent in practice (eg most conduct) and many others in Commonwealth legislation are technical/jurisdictional elements with no relevance to responsibility. The relevant question is whether or not absolute/strict liability applies to any element of a Commonwealth offence that may plausibly be committed without subjective intent or knowledge and that is relevant to criminal responsibility.^[24]

10.21  Accordingly, this chapter focuses on laws which impose strict or absolute liability on physical elements that would normally require fault to render them culpable.