Questionnaires being sent out to the attendees of Downing Street parties that may have broken Covid laws will be the written equivalent of police interviews under caution.
More than 50 politicians and staff have been given a week to respond to the formal documents by email, and police will then decide whether to fine them for breaking restrictions.
The penalties could vary between £100 and £10,000, depending on the law that was in force at the time, the size of the gathering and the person’s role.
Prosecutions may follow if people refuse to pay any fines issued to them, and police decide to pursue further action.
The Metropolitan Police said the questionnaires demand “an account and explanation of the recipient’s participation in an event”.
The force said the documents “have formal legal status and must be answered truthfully”.
A spokesperson told The Independent that answers “will be treated as written statements made under caution”.
Police cautions are used when people are suspected of a criminal offence, and warn them: “You do not have to say anything, but it may harm your defence if you do not mention, when questioned, something which you later rely on in court. Anything you do say may be given in evidence.”
A criminal barrister told The Independent that the questionnaire process was “almost unheard of”, as police normally interview people in person.
Andrew Keogh said the questionnaires appeared to be the equivalent of an in-person interview under caution, “but done on paper with fixed questions”.
“When police interview someone they caution them,” he added. “It doesn't matter if it’s said by a police officer in front of you who’s writing down what you’re saying, which is the normal way, or if you’re sent a questionnaire with that written at the top.”
Mr Keogh said that to establish whether there was a defence to Covid offences under the Health Protection Regulations, recipients may be asked specific questions on how long they spent at gatherings and whether there was a “reasonable excuse” for their attendance in law.
“It gives the opportunity for people to give a defence or a complete denial,” he added.
The barrister said that there was no law against people who attended the same event discussing their accounts with each other before responding to the questionnaire, “but there is a line between a legitimate collating of experiences and a conspiracy to pervert the course of justice”.
Mr Keogh said it would be “absolutely normal” to seek legal advice before responding to the questionnaires, as people would be offered representation at any in-person police interview.
He also explained that there was no legal obligation for people to answer the Metropolitan Police’s questions.
“I can’t believe anybody would actually fill in one of these statements, unless there is a killer defence,” he added.
Adam Wagner, a lawyer who has been studying Covid-19 regulations, described the dispatching of questionnaires as “very significant” because it means the police believe they have evidence of criminal offences.
He told BBC Radio 4’s Today programme that because Boris Johnson allegedly attended up to six gatherings, he could “be in line for over £10,000 worth of fixed penalty notices if they accumulate”.
The Metropolitan Police is currently investigating 12 gatherings on eight dates between May 2020 and April 2021, including a Downing Street Christmas party and a birthday celebration for the prime minister.
Detectives are considering adding a festive quiz held by No 10 on 15 December 2020 to the tally, after the Daily Mirror published a new photo showing Mr Johnson and two other people around a table with sparkling wine and crisps.
“Detectives, working for the Met’s Special Enquiry Team, continue to examine more than 500 documents and 300 images provided to them by the Cabinet Office and will be requesting further information to assist with the investigation,” a Scotland Yard spokesperson said.
“There may be a need to contact further people in the coming days and weeks - should they be identified as having taken part in an event and having potentially breached regulations.
“It should be noted that being contacted does not mean a fixed penalty notice will necessarily be issued to that person.”
Mr Johnson has refused to say whether he will resign if he is fined for breaking the law, as stark criticism from former prime minister Sir John Major added to mounting pressure on Thursday.
“That process must be completed and I'm looking forward to it being completed and that's the time to say more on that,” he told reporters in Brussels.
Further Conservative MPs are poised to call for a vote of no confidence in the prime minister if he is fined, or further damaging details emerge from the Sue Gray inquiry.
