Tattoos and Copyright Infringement: An intriguing debate

Came across an interesting article in the NY Times, about tattoos and copyright infringement.  The article details several lawsuits that have arisen as a result of video game developers using images of athletes and their tattoos. 

It never occurred to me that the tattoo artist retains his or her creative rights, even if the canvas upon which their art is a human being.  As a writer, I can understand the artists' desire to protect their work, but I always assumed tattoos would fall under a "work for hire/all rights" umbrella.  

Then, I did a little more reading on the subject, and found this article, about a lawsuit that arose as a result of a sight gag in the movie The Hangover II. One of the characters gets a tribal face tattoo that is exactly like boxer Mike Tyson's.  The artwork is distinctive and instantly recognizable--and the artist demanded compensation.   The movie studio eventually reached a financial settlement with the tattoo artist, and I think it was the right move.   It does raise some questions, though, about who owns the rights to artwork that appears on the human body--at some point, depending on the medium, does an artist relinquish their right to their art being reproduced?