Universal Music Group, Aftermath Records and Interscope Records appealed against a ruling in the Ninth Circuit Court of Appeals in December that said they should pay 50% of royalties on digital sales rather than 12-20%.
It dates back to a suit brought by FBT Production, which originally signed the rapper in 1995.
In September, the Ninth Circuit held that a previous district court ruling "had improperly denied FBT's motion for summary judgment". This meant that the downloads were classed as "licences" rather than traditional sales.
Detroit Free Press quotes Joel Martin of FBT as saying, "For us, this is probably a $40m to $50m [?24.6m to £30.77m] issue. Every artist who has this sort of language in their contract is now going to go back to their record company and say, 'OK, so what do you want to do about [download royalties]?'"
In a statement, Universal spokesman Peter Lofrumento said, "The case has always been about one agreement with very unique language. As it has been made clear during this case, the ruling has no bearing on any other recording agreement and does not create any legal precedent."