Hundreds of post office operators are to have their convictions quashed by parliament within months in an unprecedented move designed to draw a line under one of the biggest miscarriages of justice in British history. Senior lawyers said, however, that the decision to pass a bill overturning so many court verdicts was constitutionally extraordinary and risked undermining the independence of the judiciary if it was seen as a precedent for future cases. Announcing the move, less than a week after the broadcast of an ITV drama that catapulted the long-running saga into the political mainstream, Rishi Sunak told the Commons that the legislation would acquit all those convicted in the Horizon IT scandal. Anyone who has their conviction overturned will be given an upfront offer of £600,000 or allowed to proceed with a detailed assessment process if they feel they are owed more. Those who are part of a separate group litigation, who have already received some money, will be offered £75,000 each. It was reported that the bill of at least £450m would be footed by the taxpayer. Setting out details of the plan to MPs, the business minister responsible for postal affairs, Kevin Hollinrake, conceded that the blanket approach could mean some people fraudulently receiving compensation but that the risk was worth it to end the long wait. “This is one of the greatest miscarriages of justice in our nation’s history,” Sunak said during prime minister’s questions. “People who worked hard to serve their communities had their lives and their reputations destroyed through absolutely no fault of their own. The victims must get justice and compensation.” He added: “We will make sure that the truth comes to light, we right the wrongs of the past and the victims get the justice they deserve.” The announcement was greeted with approval from Alan Bates – the postmaster who has campaigned for 20 years to expose the scandal. “It’s about time, this was the decent thing to do,” he told the Times. “We’ve got the whole country behind us now. There’s still a lot of work to do. Once a job’s done, the job’s done, and we can relax a bit — but we’re not there yet.” The plan also won immediate backing from Labour, meaning it will pass parliament without hindrance. However, legal organisations said ministers should give assurances to parliament, and within the bill, that this was a one-off. David McNeill from the Law Society said: “Are we feeling queasy about it? Are we looking down with a sort of queasy sense of vertigo? Yes, we are. It breaches a fundamental principle which is effectively the government legislating against decisions, against the independence of the courts. “These are exceptional circumstances, it is an extraordinary measure. It must not, must never, be seen as a precedent.” Sam Townend KC, the chair of the Bar Council, said: “We will examine the proposals carefully. Anxious care should be taken as to ensuring the independence of the judiciary and the government must be careful about setting legal and constitutional precedent.” Downing Street said: “We don’t take this step lightly and have consulted with the judiciary.” Later Scotland’s first minister Humza Yousaf confirmed that everyone convicted in Scotland as part of the scandal would likewise be cleared. Writing to Sunak, he said he wanted to work with the UK government to ensure victims across the UK were exonerated. Usually a law such as the one proposed by Sunak to quash the convictions would not have effect in Scotland, but Yousaf indicated that a legislative consent motion approved in the Scottish parliament would be the quickest way of ensuring that it did apply north of the border. Speaking to the BBC on Wednesday evening, Hollinrake accepted that the pace of the response had been sped along by the ITV drama Mr Bates vs the Post Office, broadcast in four parts last week, which told the story of Alan Bates, the post office operator who led the campaign against the injustice. “Of course we respond to public pressure. That’s what we’re here for,” Hollinrake said. “This is government. Things go on the ‘too difficult’ pile. There’s lots of different stakeholders involved in government.” While the plan will swiftly clear and compensate the more than 900 people prosecuted by the Post Office after being wrongly accused of taking money between 1999 and 2015, a parallel political row is still raging over responsibility for the affair. Sunak’s announcement of the plan was made in response to a seemingly planted question from Lee Anderson, the Tory party deputy chair, who called for Ed Davey, who was minister responsible for postal affairs from 2010 to 2012, to quit as Liberal Democrat leader. However, attention has also fallen on the Conservatives’ links to Fujitsu, which provided the faulty Horizon accounting software, on which the convictions were based. Simon Blagden, a Conservative donor who chairs the government’s Building Digital UK agency, was described by Fujitsu UK in 2015 as a member of its leadership team who sat on its UK and Ireland responsible business board, as well as being chair of one of its subsidiaries, Fujitsu Telecommunications, for 14 years from 2004 to 2019. The government said Blagden was “in no way involved” in the Horizon project and Fujitsu Telecommunications was “a separate organisation”. There are also tricky questions for some Whitehall officials about their oversight of the Post Office, including civil servants who sat on its board on behalf of the government. Susannah Storey, now permanent secretary of the Department for Culture, Media and Sport, and Richard Callard and Tom Cooper of UK Government Investments, were non-executive directors of the Post Office and are highly likely to be called to give evidence in the ongoing public inquiry into the convictions. Setting out the plan in the Commons immediately after Sunak spoke, Hollinrake said post office operators convicted during the relevant period would be asked to sign a statement declaring they did not commit a crime and could be prosecuted for fraud if this was false. “I do not pretend to the house that this is a foolproof device, but it is a proportionate one which respects the ordeal with which these people have already suffered,” he said. The two different classes of compensation, £600,000 and £75,000, reflect the fact that the second group, numbering 555 people, were part of a group legal action that received a settlement from the Post Office in 2019. Much of their £43m payout went to legal costs, and those in the group who believe they are entitled to more than £75,000 can also go through the assessment process. Hollinrake said he expected those who were prosecuted after taking part in a pilot scheme of the software would also be eligible for compensation. The Post Office, which has the power to instigate prosecutions, prosecuted more than 900 branch owner-operators based on information from the Horizon system. While it eventually conceded fault, as of December just 142 appeal case reviews had been completed. Of these 93 convictions were overturned, with 54 upheld, withdrawn or refused permission to appeal.