Presumption of culpable mental state shifts burden to accused to prove absence of intent in GST offences. The court shall presume existence of a culpable mental state in prosecutions requiring such an element, but it is a defence for the accused to prove absence of that mental state regarding the charged act; 'culpable mental state' includes intention, motive, knowledge, and belief or reason to believe a fact, and a fact is proved only when the court believes it exists beyond reasonable doubt, not by a preponderance of probability.