ReDigi has been at loggerheads with major labels and publishers in recent years thanks to its attempts to establish a second hand digital market for mp3 files.

Now the company has secured a new patent in the US that could force music companies to reassert and redefine their opposition to the concept.

EMI sued ReDigi at the beginning of 2012 after the tech firm unveiled what it called “the world’s one and only online marketplace for digital media”.

The platform ...