No particular form of instruction to the jury is required where the evidence on one or more elements of the offence is entirely or primarily circumstantial. However, where proof of one or more elements of the offence depends solely or largely on circumstantial evidence, it may be helpful for the jury to receive instructions that will assist them to understand the nature of circumstantial evidence and the relationship between proof by circumstantial evidence and the requirement of proof beyond reasonable doubt.
An explanation of the difference between direct and circumstantial evidence is included in most criminal jury charges and rarely causes difficulty. An instruction concerning the use of circumstantial evidence and the reasonable doubt instruction have different, although related, purposes. The reasonable doubt instruction describes a state of mind — the degree of persuasion that entitles and requires a juror to find an accused guilty. An instruction about circumstantial evidence, in contrast, alerts the jury to the dangers of the path of reasoning involved in drawing inferences from circumstantial evidence. Telling the jury that an inference of guilt drawn from circumstantial evidence should be the only reasonable inference that such evidence permits will often be a succinct and accurate way of helping the jury to guard against the risk of "filling in the blanks" by too quickly overlooking reasonable alternative inferences. While this Court has used the words "rational" and "reasonable" interchangeably to describe the potential inferences, there is an advantage of using the word "reasonable" to avoid the risk of confusion between the reasonable doubt standard and inferences that may arise from circumstantial evidence. However, using the traditional term "rational" is not an error as the necessary message may be imparted in different ways.