In surely one of the most bizarre stories of recent weeks, former FC Barcelona president Sandro Rosell was forced to deny claims he illegally purchased a human liver for ex-defender Eric Abidal in 2012, after a report in Spanish newspaper El Confidencial claimed police had intercepted phone calls of Rosell allegedly admitting the purchase.A statement by FC Barcelona flatly denied the allegations, and pointed out that a Catalan court had shelved an investigation into the matter in 2017. Further firm denials were issued by Abidal and the hospital in which he underwent surgery, while Spain’s National Transplant Organisation also came forward to confirm that the operation was performed in accordance with the law.In this case it appears clear that the transplant was legal, but the incident does shine a spotlight on commercial organ transplantation and the murky worldwide black market for human organs. But what is this trade and how often does it happen?