E.U. and U.K law both refer to copyright as a property law (THE EUROPEAN PARLIAMENT AND COUNCIL 2001 3; Great Britain 1988 1(1)). U.S. courts also look upon copyright as an ownership of property (Netanel 2008 p.7).
Once a right is a property, it is the same as any physical property under the law. Therefore, the main means of making money for the copyright industry is to protect the copyright they have purchased as though it were a property. This has nothing to do with protecting the copyright in the artistic sense, but in protecting copyright in its commodified sense by protecting the right to exploit creative work.
The processes by which the message is contained within a given medium are legally physical property. While it may be hard to equate shoplifting with digital downloading, this is an accurate legal model. The downloader is ‘shoplifting’ the physical reproduction and distribution rights from that one copy – rights that underpin the copyright industries.