If he is ever successfully prosecuted for misconduct in public office, Lord Peter Mandelson would become the first former UK government minister to be convicted of the offence, according to legal experts.
Police are investigating the veteran Labour politician and former UK ambassador to the US over allegations that he passed sensitive government information to sex offender Jeffrey Epstein when he was business secretary under Gordon Brown in 2009 and 2010.
Emails released by the US justice department are alleged to show Mandelson passing on market-sensitive information to the disgraced American financier, including details of a €500bn EU bailout of the Eurozone.
However, lawyers said the charges being investigated had a high bar for conviction. No charges have yet been brought against Mandelson and neither has there been an arrest.
What is the offence?
Misconduct in public office, which carries a maximum sentence of life imprisonment, has not been defined by statute. Rather, it is a common-law offence, developed by judges over hundreds of years.
To secure a conviction, prosecutors must demonstrate four elements. The first — that the suspect must have been acting in their capacity as a public officer at the time of the alleged misconduct — would appear to be straightforward in Mandelson’s case as he was a government minister.
More substantively, the office holder must have acted “wilfully” — they deliberately did something wrong or were indifferent to the consequences. The prosecution must also demonstrate there was no reasonable excuse.
Lawyers said the biggest barrier for prosecutors was the need to demonstrate the alleged misconduct amounted to an “abuse of the public’s trust”, meaning it was serious enough to warrant a criminal prosecution rather than disciplinary sanction.
Who has been prosecuted?
Prosecutors brought 521 cases in England and Wales between 2014 and 2024 in which misconduct in public office was the sole principal offence, according to Ministry of Justice-cited data by Spotlight on Corruption. They secured 362 convictions.
Critics of the law say it has largely been a tool for policing the rank-and-file rather than holding power to account. The large majority of cases have involved relatively junior workers, according to Spotlight on Corruption.
Those working on the front lines of the criminal justice system are typical targets, often police officers accused of having sexual relationships with crime victims or suspects.
Prison staff face similar scrutiny for having inappropriate relationships with inmates. They have also been prosecuted for offences such as smuggling contraband.
Among the handful of senior figures to be convicted for misconduct in public office are a bishop who was convicted of sexual offences and a Ministry of Defence official who was jailed for receiving kickbacks.
The political class has remained largely untouched: although a small number of politicians have been arrested, none in modern history have been convicted for misconduct in public office, legal experts said.
In 2008, Damian Green was arrested and questioned by police in connection with information allegedly leaked to newspapers about government immigration policy.
The operation, in which counter-terrorist officers searched the Tory frontbencher’s parliamentary offices while he was in opposition, precipitated a serious political dispute.
Prime Minister Sir Keir Starmer was director of public prosecutions at the time and decided not to bring charges. He said there was a “high threshold before criminal proceedings can properly be brought”.
Why is the bar so high?
While many are clamouring for action against Mandelson, some lawyers said the legal establishment was cautious about “weaponising” the law against political figures.
The courts are wary of being seen to criminalise political activity, particularly when it comes to parliamentarians receiving and disclosing information, legal experts said.
“There’s no precedent . . . for a prosecution [on this charge] of a minister of state,” said Jeremy Horder, professor of criminal law at the London School of Economics.
More broadly, Horder added, “there’s a risk of improper pressure being brought to bear on prosecutors, for political reasons. That makes a prosecutor’s job very difficult.”
The Law Commission, in a review published in 2020, said the law was “notoriously difficult” to define, creating legal uncertainty.
The commission, which recommends legal reforms, was critical of its use as a “catch-all” charge rather than a specific offence. It also raised concerns that the law bites against “relatively junior officials, rather than more senior decision makers that members of the public might more readily expect to be held criminally accountable”.
What does all this mean for Mandelson?
Tom Frost, senior lecturer in law at Loughborough University, said it was “unlikely” that Mandelson would ever be convicted of misconduct in public office.
“With a politician, there’s a very high bar to charge for this offence,” he said. “No MP has ever been convicted of it.”
However, Frost said that police could end up arresting Mandelson on other charges depending on any evidence they uncovered.
“Just because they say they are investigating one offence, [it] doesn’t preclude the police charging you on any other offence,” he added. “The police will go wherever the evidence takes them.”
Scotland Yard last week said its investigation would be “complex” and would require “a significant amount of further evidence gathering and analysis”.
The force added: “It will take some time to do this work comprehensively.”