What happened
The Hillsborough disaster of 15 April 1989 was caused by police failures in crowd management — a fact not formally established for over two decades because of an organised cover-up in which sections of the press were active participants.
The Sun's 19 April front page was the most notorious product of that cover-up. Its claims were sourced from South Yorkshire Police officers via the Sheffield-based Whites News Agency, with Conservative MP Irvine Patnick among those relaying the false accounts. Other papers ran the same briefings; only The Sun presented them as "THE TRUTH".
The 2012 Hillsborough Independent Panel, given access to over 450,000 documents, found that fans were entirely blameless, that 116 of 164 police statements had been amended to remove criticism of the police, and that the smear campaign was coordinated. The 2016 inquests ruled the 97 were unlawfully killed.
The media-accountability significance: a mass-circulation newspaper printed a police force's self-exculpatory lies about the newly dead, unverified, under a banner asserting certainty — and faced no regulatory consequence for 23 years. Editor Kelvin MacKenzie's various retractions were partial and repeatedly withdrawn. Merseyside's boycott of The Sun, sustained for over three decades, remains the only sanction that ever held.
Evidentiary class: official inquiry finding (Hillsborough Independent Panel, 2012) and inquest verdict (2016).