Chapter 5 Likelihood ratio to evaluate uncertainty

Using the theory of probability and propositions, we have seen how uncertainty can be described and framed around the key facts of a criminal case. The final idea is to evaluate the uncertainty surrounding evidence in a way which satisfies probability theory, so that it remains logically consistent, and also so that it assists the court in determining the truth of key propositions. This is achieved using the likelihood ratio.

In this chapter, we focus on the likelihood ratio in detail. We revisit how it relates to probabilities, propositions, and evidence, how it is used to quantify probative value, what factors can affect its robustness, and how it is categorised and communicated to the court.