The "Die Hard" actor is apparently preparing to sue Apple over the rights to his iTunes music library after his death.
Willis is upset because, when he dies, he technically can't pass his extensive collection of iTunes tracks down to his children, according to the Sun,
See, when you download a song using iTunes, you get a copy of the song and a so-called nontransferable license to listen to it, according to the Terms of Service. This means that when you copy a song purchased using iTunes and share it with a friend, you're technically breaking the legal agreement. (Of course, like many other people, you may not care.)
However, it also means that once you're dead, that license expires -- and, from a very strict legal point of view, nobody else can listen to the songs in your iTunes music library. Like you, Bruce Willis cannot hand down his music collection in the event of his death (probably at the hands of German terrorists).
In the past, iTunes purchases were much more restrictive than they are now. In those days, any songs downloaded using iTunes came with digital rights management, or DRM, specifications attached. This meant that to play an iTunes audio file, you had to "license" it to a specific computer. Once you hit five computers, you couldn't play it anywhere else.
All that changed a while back: Apple now offers non-DRM files, meaning you can copy and share them as many times as you like with no restrictions.
However, that doesn't change the fact that when you buy a song from iTunes, you're technically -- according to the Terms of Service -- purchasing a license to listen to that song. And that Apple can technically freeze the account of someone suspected of rampant file sharing, although this is a pretty uncommon occurrence.
VentureBeat pointed out these rules were largely put in place at the behest of the major record labels represented by the Recording Industry Association of America to fight piracy, even though these small legal aspects are often overlooked by the public at large.
All that said, there's really nothing stopping Willis from simply leaving his children a hard drive full of music in his will. It may be illegal, but only in a very technical sense. Plus, who is going to stop Bruce Willis from doing whatever he wants? Everyone saw what happened to Hans Gruber.