 This notion is crucial in legal applications. The fact-finders at trial might want to know the probability of “The defendant was at the scene when the crime was committed” conditional on “Mrs. Dale asserts she saw the defendant run away from the scene”. Or they might want to know the probability of “The defendant is the source of the traces found at the crime scene” conditional on “The DNA expert asserts that the defendant’s DNA matches the traces at the scene.” In general, the fact-finders are interested in the probability of a given hypothesis \(H\) about what happened conditional on the available evidence \(E\), in symbols, \(\Pr(H \pmid E)\).