回复：不懂就问

Good question. Normally a defamation is under strict liability that proof of actual fault of the defendant is not required. However, the US Supreme Court held that when the defamation was on a public figure or public official, the actual fault must be proven in order to protect the 1st Amandment of free speech. The actor would have made a false statement on a material fact about the victim, with malice fault, and resulted in (1) lowered estimation of the victim, or (2) deterrence of other of association with the victim (Restatement). Usually courts will hold a hatred statement suffice for defamation. A joke will never do.