Willis, of Die Hard fame, has reportedly spent thousands of dollars on digital music, which he wants to leave to daughters Rumer, 24, Scout, 20, and Tallaluh, 18.

Existing iTunes rules mean he cannot do so because bought music is only "borrowed" under a licence.

If Willis is able to challenge the small print successfully, it might benefit millions of frustrated iTunes users who have not had the resources to fight the technology giant.

His first option would be asking his lawyers to establish a family trust to hold the downloads. He could also support legal tussles in other US states where complainants are seeking to gain more rights to their music.

With more and more people buying digital media products, the issue of ownership is becoming an increasing problem, with many not realising they do not hold the rights to their books, music, films or games.

Legal expert Chris Walton said: "The law will catch up, but ideally Apple and the like will update their policies and work out the best solution for their customers."