Definition from Nolo’s Plain-English Law Dictionary
A statement of opinion (no matter how ludicrous) based on facts which are correctly stated, and which does not allege dishonorable motives on the part of the target of the comment. The U.S. Supreme Court has ruled that to protect free speech, statements made about a public person (politician, officeholder, movie star, author, etc.), even though untrue and harmful, are fair comment unless the victim can prove the opinions were stated maliciously -- with hate, dislike, intent, or desire to harm. Fair comment is a crucial defense used by members of the media against libel suits.