This is not to say that direct evidence is more reliable or always more persuasive. Its persuasiveness derives not from its directness but from its ring of truth and accuracy. If it does not ring true, direct evidence is often outweighed by evidence that is wholly circumstantial. The principal requirement of evidence is that it be relevant. That is to say, the information offered must have some tendency to prove or disprove some disputed question of fact.
Direct evidence is always relevant.
The offer of circumstantial evidence, on the other hand, forces a court to examine its probative quality. In some instances, the decision to admit circumstantial evidence will turn altogether on precedent. In prosecutions for murder, for example, courts long ago determined that evidence of flight has some tendency to prove a consciousness of guilt and that consciousness of guilt in turn has some tendency to prove guilt itself. Accordingly, a judge will admit such evidence without freshly examining its relevance. Where precedent is lacking, a judge must rely on logic, experience, and common sense.