Best evidence?
From Create Your Own Story
"Okay, this is the last one, unless you didn't go in order like a foolish fool. This is where a witness is asked to state or describe something about a currently observable piece of evidence. For example, say the victim's diary was found at the scene..."
Lawyer: Can you tell us what the diary looked like? Prosecutor: OBJECTION! According to the best evidence law, we must observe the diary directly!