Technically, WinMX is perfectly legal. WinMX is merely a PTP file-sharing service. PTP file-sharing services are simple in concept: they allow connected users to share files with each other. The more connected users, the more files there will likely be to share. However, how you use a PTP service, like WinMX, may be illegal. Huh, you ask?

In short, it is illegal for you to use WinMX to share copyrighted files without the owner’s permission. For example, you cannot allow other users on WinMX to download your music files if those music files are not owned by you (or an exception applies, like the music is in the publish domain or you receive consent from the owner). Also, buying the music file does not mean you "own" the file. This is often a great misconception. When you buy a music file (like on iTunes) or a CD, you merely buy the license to listen to the songs--but you have no actual authority to transfer those songs to others.

Violating copyright law is called copyright infringement and can carry with it some hefty civil and even criminal penalties, including jail time.

Next, let’s take a look at WinMX’s run-in with the Record Industry Association of America.