Strict Liability

This lesson covers strict liability offences — crimes where the prosecution does not need to prove mens rea in relation to one or more elements of the actus reus. You need to understand the nature of strict liability, how courts determine whether an offence is one of strict liability using the Gammon criteria, key statutory examples, and the arguments for and against imposing liability without fault.

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Key Terms

Term	Definition
Strict liability	An offence where no mens rea is required for at least one element of the actus reus
Absolute liability	An offence where no mens rea is required at all and no defence is available — extremely rare
Presumption of mens rea	Courts presume that Parliament intended mens rea to be required unless the contrary is clearly indicated
Gammon criteria	A set of guidelines established in Gammon v AG of Hong Kong [1985] for determining whether an offence is one of strict liability
Regulatory offence	An offence concerned with the regulation of activities (e.g., food safety, road traffic, pollution) rather than "true" criminal conduct
Due diligence defence	A statutory defence allowing the defendant to escape liability by proving they took all reasonable precautions

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What Is Strict Liability?

A strict liability offence is one where the prosecution does not need to prove mens rea in respect of at least one element of the actus reus. The defendant can be convicted even though they did not intend, foresee, or even know about the element in question.

It is important to distinguish strict liability from absolute liability:

• Strict liability: No mens rea required for one or more elements, but the actus reus must still be voluntary and some defences may still be available.
• Absolute liability: No mens rea required at all and no defences available. This is extremely rare (e.g., Winzar v Chief Constable of Kent [1983] — being found drunk on the highway, even though police had placed the defendant there).

The Presumption of Mens Rea

The courts start from the position that Parliament intended mens rea to be required for criminal offences. This is known as the presumption of mens rea (or the presumption of innocence). The leading authority is:

Sweet v Parsley [1970]

Ms Sweet rented out rooms in a farmhouse. Tenants used the premises for smoking cannabis without her knowledge. She was convicted of "being concerned in the management of premises used for the purpose of smoking cannabis" under the Dangerous Drugs Act 1965. The House of Lords quashed her conviction, holding that the offence required mens rea. Lord Reid stated:

"There has for centuries been a presumption that Parliament did not intend to make criminals of persons who were in no way blameworthy in what they did."

Principle: There is a strong presumption that mens rea is required. The presumption can only be displaced if this is clearly or by necessary implication the effect of the statute.

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The Gammon Criteria

The most important framework for determining whether a statutory offence is one of strict liability was established in:

Gammon (Hong Kong) Ltd v Attorney General of Hong Kong [1985]

The Privy Council set out five propositions (the "Gammon criteria"):

No.	Criterion
1	There is a presumption of law that mens rea is required before a person can be guilty of a criminal offence.
2	The presumption is particularly strong where the offence is "truly criminal" in character.
3	The presumption can only be displaced if this is clearly or by necessary implication the effect of the statute.
4	The only situation in which the presumption can be displaced is where the statute is concerned with an issue of social concern.
5	Even where a statute is concerned with social concern, the presumption stands unless strict liability will be effective to promote the objects of the statute by encouraging greater vigilance to prevent the commission of the prohibited act.

Applying the Gammon Criteria: A Decision Flowchart

flowchart TD
    A[Start: Does the statute expressly require mens rea?] -->|Yes — e.g., 'knowingly', 'intentionally', 'recklessly'| B[Mens rea required — NOT strict liability]
    A -->|No — statute is silent on mens rea| C{Is the offence truly criminal in character?}
    C -->|Yes — e.g., serious personal harm| D[Strong presumption of mens rea — unlikely to be strict liability]
    C -->|No — regulatory / quasi-criminal| E{Is the offence concerned with an issue of social concern?}
    E -->|No| F[Presumption of mens rea applies — NOT strict liability]
    E -->|Yes — e.g., public safety, food, environment, drugs| G{Would strict liability promote the objects of the statute?}
    G -->|Yes — encourages greater vigilance| H[Strict liability likely applies]
    G -->|No — strict liability would not help| F

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Key Statutory Examples

Pharmaceutical Society of Great Britain v Storkwain [1986]

A pharmacist dispensed prescription drugs on the basis of forged prescriptions. The pharmacist had no reason to suspect the prescriptions were forged and had acted honestly throughout. Nevertheless, the House of Lords held that the offence under s.58(2) of the Medicines Act 1968 was one of strict liability. The pharmacist was convicted despite having no mens rea in relation to the prescriptions being forged.

Significance: Demonstrates how strict liability can impose criminal liability on professionals who act honestly and reasonably. The justification is that the supply of prescription drugs is a matter of public safety and pharmacists must be encouraged to be extremely vigilant.

Callow v Tillstone [1900]

A butcher asked a veterinary surgeon to inspect a carcass. The vet certified it as sound, but it was in fact unfit for human consumption. The butcher was convicted of exposing unsound meat for sale, despite having relied on expert advice and having no reason to believe the meat was unsound.