One of the murkier and most difficult-to-pin-down ways of illegally obtaining music right now are websites that convert YouTube streams to MP3s, and now one of the more prominent sites is being sued by Universal, Warner Bros, Sony and a number of other record labels, according to The Hollywood Reporter. YouTube-mp3.org, which is apparently run by a German company owned by Philip Matesanz, was sued in California federal court today. The lawsuit alleges that the site is responsible for “40% of all unlawful stream ripping that takes place in the world” and that “tens, or even hundreds, of millions of tracks are illegally copied and distributed by stream ripping services each month.”

The lawsuit, which can be seen in full here, goes on to state: “Stream ripping has become a major threat to the music industry, functioning as an unlawful substitute for the purchase of recorded music and the purchase of subscriptions to authorized streaming services.”

According to The Hollywood Reporter, the suit “demands an order that would also enjoin web hosts, domain-name registrars and other third parties from facilitating access to youtube-mp3.org” and that the labels involved are “seeking statutory damages and costs.”