As technology has grown, the issues around sampling have become yet more complex.
The Weeknd's 'Belong To The World' for example, sounded for all the world as if it sampled Portishead's 'Machine Gun'. Yet Abel Tesfaye argued that no sampling was necessary - it was simply a re-creation, and thus no credit was due.
Portishead's Geoff Barrow protested, stating: "When someone asks to sample you and you refuse they should have the respect as a fellow artist to not use it."
Now the producer has followed this by producing a letter - ostensibly from The Weeknd's team - asking for permission to sample 'Machine Gun'.
The picture it paints is that the Canadian artist asked for permission, was denied it, and subsequently went over the band's head anyway. Check out the letter below.