New powers to help the investigation of police officers involved in the Hillsborough disaster have been approved by MPs in the Commons.
The actions of up to 2,400 serving or retired officers could be considered by the Independent Police Complaints Commission (IPCC) investigation.
The Police (Complaints and Conduct) Bill would grant the IPCC new powers.
It will mean police officers and staff would be compelled to testify as witnesses in IPCC investigations.
It will also mean that in exceptional circumstances the IPCC could investigate a matter that has already been investigated by its predecessor body, the Police Complaints Authority.
'Truth to justice'
The emergency legislation was put forward by the government to help the IPCC in its investigation into the police's response to the Hillsborough disaster.
The inquiry was prompted by the Independent Hillsborough Panel Report, released in September, which found police and emergency services had made "strenuous attempts" to deflect the blame for the disaster on to fans.
The panel revealed 164 police statements had been altered - 116 of them to remove or change negative comments about the policing of the FA Cup semi-final between Liverpool and Nottingham Forest at the Sheffield stadium.
The bill had cross-party support and cleared the House of Commons in less than four hours, receiving its second and third readings without a vote.
It must now be approved by the House of Lords.
Speaking in the Commons, Policing Minister Damian Green said: "The conclusions of the independent panel's report were deeply distressing: the failure of the authorities to protect the fans, the attempts to blame them and the doubts cast on the original coroner's inquests are all particularly troubling findings.
"As the Bishop of Liverpool has said, we now need to move from truth to justice and it is this move that is at the centre of the bill before us today."
Mr Green said if the bill were passed, he was sure any officer who failed to comply would face disciplinary action and could be dismissed.
The IPCC would not have the same power to compel retired officers to appear as witnesses, but Mr Green said he would expect them to attend willingly.