When is a resale not a resale? That's the question being mulled over by US lawmakers this evening, as EMI's lawsuit against digital music site ReDigi heads towards a crucial conclusion.

The decision could set a precedent for whether sites are allowed to sell 'second-hand' digital music files in future - and cut labels out of the value chain.

Launched in October 2011, ReDigi claims it is the first legal site that lets users can buy second-hand music files - ...