$4.$ The Hangover Part II has been a hotbed of intellec$-$ tual property issues. Last summer, Warner Brothers settled a lawsuit brought by the tattoo artist who did Mike Tyson's facial tattoo that was then replicated on a character in the movie. Now, Louis Vuitton has filed suit in federal court for trademark infringement of its famous bags.

The ne'er$-$do$-$well character played by Zach Galifi$-$ anakis has coined a pop$-$culture phrase by warning his fellow imbibers when they touch his Louis Vuitton bag, "Careful, that is a Louis Vuitton." The lawsuit seeks to have the trademark bag excised from the film as well as a share of the movie's profits. The company seems most irritated because it alleges that the bag used in the movie is a knock$-$off. Louis Vuitton is very aggressive in enforc$-$ ing its trademark rights and has brought suit against art$-$ ists who have used the signature handbags and luggage in their paintings.

What is the issue in the use of trademarked products in artistic works? Why is Louis Vuitton so concerned about the use of its products in a film such as The Hang$-$ over Part II$?$