A trio of recent articles (Tillers & Gottfried, 2006 (TG Franklin, 2006 (Franklin); Weinstein & Dewsbury, 2006 (Weinstein)) in this journal concerning the quantification of the ‘reasonable doubt’ standard of criminal law has prompted me to express these brief comments. From different perspectives, these authors have interestingly discussed the issues of whether the ‘reasonable doubt’ standard can be quantified and whether quantification, however expressed, should be presented to juries considering whether a defendant’s guilt has been proven by the requisite standard. Without joining the debate on these issues, I write to suggest that all these distinguished authors have not brought sufficient clarity to exactly what it is they believe should be quantified and communicated to juries. Judge Weinstein says that he would like to tell a jury, ‘Were I the trier of fact, I would require a probability of guilt of no less than 95%.’ (Weinstein at 7, emphasis added). Professors Tillers and Gottfried refer to ‘quantification of the reasonable doubt standard in terms of odds, probabilities or chances’ and provide an example of an instruction that permits a juror to convict ‘only if the juror believes that there is more than a 95% chance that the defendant is guilty.’ (T & G at 9, emphases added). Professor Franklin suggests that ‘any probability less than 0.8 should be declared less than proof beyond reasonable doubt in all circumstances.’ (Franklin at 2, emphasis added). My concern is that words such as ‘probability’, ‘odds’ and ‘chances’ are not clear to the average juror. Indeed, as used by these writers, they are not clear to me. Let me first explain why uncertainty arises in my mind, and, I suspect, may well arise in the minds of jurors, and then turn to a verbal formulation that I think might be preferable, regardless of the percentage selected. For many people ‘probability’ will mean the degree of likelihood that a future event will occur. For example, a person considering whether the toss of a coin will come up heads or tails could be expected to say that the probability of heads is 50%, by which he or she might well understand that if the coin is tossed 100 times, it will come up heads 50 times. What is that person supposed to think if, serving as a juror, he is told, in the formulation of Judge Weinstein, that a probability of guilt must be 95%? What is the future event that will happen 95 times out of 100, comparable to the 50% probability that a tossed coin will come up heads? Of course, there is none. The verdict is a future event, and it has two possible outcomes—guilty and not guilty.1 But there is much greater risk of uncertainty in understanding what ‘probability’ means in the context of a jury trial than if a person is told that there is a 50% probability that the next coin toss will come up heads.