An application to quash the original Hillsborough inquest verdicts is due to be heard at the High Court on Wednesday.
Attorney General Dominic Grieve, who makes his request three months after a new report established 41 of those who died might have been saved, said the main basis for the move was new medical evidence.
Ninety-six Liverpool supporters died in the disaster at Sheffield Wednesday's Hillsborough stadium on April 15, 1989, when they met Nottingham Forest in an FA Cup semi-final.
The report revealed an extensive cover-up by police who altered witness statements to put officers in a favourable light and avert blame for the disaster on to Liverpool fans.
Some of the families of victims, who have fought to have verdicts overturned, are due to attend the hearing at the Royal Courts of Justice in central London.
There will also be a live videolink between the Royal Courts of Justice and a courtroom at Liverpool Civil and Family Courts.
Liverpool Walton MP Steve Rotheram, one of a number of MPs planning to attend the proceedings, said in a statement: "The High Court hearing is the day that the families have fought almost a quarter of a century for.
"The opportunity to quash the original inquest verdicts of accidental death seemed like an impossible task for 23 years. It is the moment they have waited over two decades for.
"My hope is that the overwhelming evidence that was uncovered in the Hillsborough Independent Panel report will be enough to emphatically prove that Hillsborough was not an accident.
"The wheels of justice turn slowly in Britain but they are beginning to gather momentum.
"This is just the beginning of a process that will see one of the greatest injustices in the last century put right and those really responsible for Hillsborough held to account."