Offences of Strict Liabilty are where a defendant would be liable for the offence for comitting the actus reus alone, no mens rea is needed.
In Harrow LBC v Shah Held comitting the actus reus of selling a lottery ticket to a minor was enough, it did not matter if the MR was present.
The courts will always try and presume that an offence requires mens rea, the first approach is to find words within the act of parliament that indicate that the MR is present. These words are intention, recklessness, knowingly and willingly.
Common Law Presumption
the common law pressumption is if the act doesnt indicate the words of MR, then the courts will presume that the mr is required for truly criminal offences.
In Sweet v Parsley : Held where a section of the act is silent, the mens rea is required for truly criminal cases.
In B v DPP: Held the presumption of mens rea is stronger the more serious the offence.
Justifications for SL are:
1) it helps protect the publoc by promoting a greater care over matter of health and safety, as seen in Alphacell v Woodward: Held the company was guilty of strict liability when putting chemicals in the river.
2) Encourages higher standards of hygeine in processing and selling food as seen in Smedley v Breed: Held strict liability was found in this regulatory offence to encourage higher standards of hygeine.
3) Makes sure businesses are run properly
4) It is easier to prove as there is no need to prove the mens rea, so it saves the courts time as people are more likely to plead guilty.
5)Protects the public as seen in R v Blake: here there was a presumption of mens rea over an issue of social concern and public safety.