US rapper Eminem's two-year-old lawsuit against his record label Universal Music has gone to trial in America.

The rapper's publishing company FBT Productions claims Eminem is owed $1.6million in unpaid royalties.

The lawsuit is centred on the royalties an artist receives when one of their songs or a ring tone is purchased online via a digital music store.

Although the payment is included in some contracts between labels and artists, in many cases it is not given the same emphasis as the royalties earned from traditional CD sales.

Lawyers for the rapper claim that digital downloads should be included in the "licensing" agreements that typically cover CDs and vinyl, which are often split 50-50 between an artist and their record label.

However, Universal claim digital sales are covered by “distribution” agreements, which can earn an artist less than 30%.

A lawyer for the Eminem told The Wrap: "If you give the music to a third party without cost to you, like manufacturing or packaging, that's the same as a licensing agreement.

"[Universal] are characterising it as something else."

The outcome of the trial could have a huge impact on the money artists earn from digital sales, which are continuing to grown in popularity.

Eminem is scheduled to release his new studio album, 'Relapse', this spring.

(by Jason Gregory)