The Taylor report (The officialenquiry into the disaster) lambasted the South Yorkshire Police Force, stating that the cause of the disaster was "The failure of police control"
Other factors, such as ticketless fans, drunken fans and crowd misbehaviour were rejected (The lack of police reaction in summoning medical aid meant that many fans attempted to treat victims themselves)
However it is acknowledged that the terrace itself was an accident waiting to happen. 31 Spurs fans were badly injured in a semi-final versues Wolves in 1981 (An event that meant Hillsborough didn't host another semi-final until 1987) Other issues such as a natural slope towards the part of the terrace where the disaster occured (Meaning crowds naturally drifted towards the fatal central pens) poor signage (Meaning fans were misguided and not informed of entrances to other, less crowded terraces) and a lack of exits meant that the situation was worsened. This is shown by the fact that Hillsborough's safety certificate had expired in 1983, six years before the disaster.
The fact that Liverpool fans recieved totally unjustified criticism is down to woefully poor media reporting of the disaster, which condemned the fans without hesitation and believed lies told by senior police officers (Again later disregarded by the Taylor report)
They were the victims of bull-headed policing and a ground that was patently unsafe.