Copyright cases aren’t usually a lotta laughs, but then, they aren’t usually about this:
https://www.youtube.com/embed/kTcRRaXV-fg
The heirs of Bud Abbot and Lou Costello claim to own the copyright in their famous “Who’s on First?” bit. They undoubtedly own the copyright on two filmed versions of the skit, because Universal Pictures gave them the copyrights on clips from two 1940s movies in which they performed it. But there are other filmed versions of the skit which are now in the public domain, the copyright protection on the movies having expired, and it is questionable whether anyone “owns” a copyright in the original skit, or indeed whether Abbot and Costello even wrote it.
Anyway, their heirs sued the author of a play in which an actor performs parts of the routine with a sock puppet. A New York state judge had to rule on a motion by the playwright to dismiss the suit on the grounds that the heirs do not own a valid copyright, and that his use of parts of the bit were “fair use” under U.S. copyright law.
In his ruling, the judge held that at this stage of the suit he must assume that the copyright is valid, but he went on to explain why he seriously doubts that is true. But he went on to rule that the play’s use of the routine was fair use because it was “transformative” — it changed the routine from a mere vaudeville skit into a commentary on life in the Bible Belt — and because it didn’t detract from the market for the copyrighted material that the heirs own, if any.
There is a good discussion of the case at techdirt.com.