Rap star Eminem's publishing companies have gone to court in an attempt to stop his songs being sold as mobile phone ringtones over the internet.
Eminem was recently treated in hospital for drug dependency
Eight Mile Style and Martin Affiliated are seeking a court order against five companies in the US District Court.
Lawyers also plan to sue karaoke firms that fail to obtain proper licences.
"This is big business," said Howard Hertz, lawyer for the publishing companies. "We're talking hundreds of thousands of dollars a year."
Eminem, one of the most successful music artists of recent years, was treated in hospital for drug dependency in August.
He had earlier announced plans to "take a break from my music to go in the studio and produce my other artists".