New laws giving extra powers to the police watchdog investigating the Hillsborough disaster and cover-up have been rushed through the House of Commons.
Policing minister Damian Green said the changes were essential to ensure the "double injustice" suffered by the victims of the 1989 disaster, as uncovered by the Hillsborough Independent Panel report published earlier this year, could be remedied.
The Police (Complaints and Conduct) Bill had cross-party support and cleared the Commons in under four hours, receiving its second and third readings without a vote.
The actions of up to 2,400 serving or retired officers could be considered by the Independent Police Complaints Commission (IPCC) investigation - the watchdog's biggest ever investigation.
The new rules, which still have to be approved by the House of Lords, would enable the IPCC to compel serving officers or staff on other police bodies to attend an interview.
It will also have the ability to reinvestigate matters already considered by its predecessor, the Police Complaints Authority, in "exceptional circumstances".
The IPCC has already announced it will be investigating the findings of the independent panel and will unusually look at both misconduct and potentially criminal behaviour by retired officers.
Mr Green said under the legal changes serving officers who refused to co-operate with the IPCC as witnesses could be dismissed, in the same way sanctions would already apply if they were the subject of an investigation.
The IPCC would not have the same power to compel a retired officer to appear as a witness, but Mr Green said he would expect them to attend willingly.
Mr Green said there had been concerns that an officer who wanted to avoid the repercussions of their actions could retire in an effort to avoid sanctions.
But he added: "This is not the case - the IPCC can and will investigate any individual suspected of criminal behaviour. It has the powers it needs to pursue these individuals and to bring them to book."