The prosecution has the burden of establishing all elements of an offence in order to prove a person has committed the offence. The majority of offences have two elements: mental (mens rea) and physical (actus reus). Discussion of such a broad and complex area of the criminal law is best left to the textbooks.
Strict liability offences are an exception to the rule that the prosecution must establish the mental element inherent in criminal offences. These offences have no mental element and only require the occurrence of the prohibited conduct for an offence to occur. Strict liability offences are usually minor offences such as speeding, driving an unregistered vehicle, or failing to wear a seatbelt. Such offences are often expiable.