JayUtah
Penultimate Amazing
Eyewitness statements are a valid form of hard evidence in a court of law.
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In the case of fact witnesses, only what the witness actually experienced with his senses is admissible. Conclusory or presumptive statements from a witness are precluded by rules of evidence. Here the witnesses heard and felt things, and drew conclusions about what had caused them. What they heard and felt is admissible. What they concluded "must" have caused it is not.
Witnesses are required in court even for such actually "hard" evidence as documentary evidence so that the origin, validity, and meaning of that evidence may be cross-examined by the opposing party. This an artifact of the adversarial process of a court trial, not a testament to the strength of eyewitness testimony. The whole point of cross-examination for eyewitnesses is to test just how "hard" that evidence is, and discover where it may have been supposed, misremembered, or fabricated.