Data - He said that I was wrong, and that "slander" can be true information used against someone.
Punk - What in blue blazes does that mean? How can you use truth against someone unjustly?
I believe true information used against someone is called blackmail.
Edit: not blackmail, defamation
Slander is oral defamation
Libel is written defamation
Both are usually based on untruth. However, defamation could be based on truth that unjustly injures another. Blackmail, of course, is the holding back knowledge of something true for gain that would be damaging to another, if such knowledge were released.
Edit 2: In the legal world, usually something must be false to be considered slander. However, this article sheds some light on this topic: "Can A True Statement Form the Basis for a Defamation Lawsuit? In a Controversial Ruling, the U.S. Court of Appeals for the First Circuit Says Yes"