The Prime Minister posted a series of tweets on Sunday morning explaining the legal background about why the attacker, Usman Khan, had been let out of prison on licence.
The tweets claim Labour policy introduced before the Tories reached office is the reason why Khan, who killed two people on Friday before being shot dead by police, was allowed out of jail after serving half his term.
A prominent anonymous legal blogger, the Secret Barrister, mocked Mr Johnson’s “weapons grade s***housery” and said the PM had “copied and pasted” the blog they wrote on Saturday.
The blogger said Mr Johnson had linked to the same document from the Prison Reform Trust and repeated an observation about “misreporting” of a judge’s comments.
They said they had considered the possibility that legal experts had drafted the tweets but said they “just can’t see it”, and added that they believed the information had come from their blog, stripped of “inconvenient context” by the Prime Minister or his advisors.
Today, the blogger also posted about justice secretary Robert Buckland’s promotion of the Prime Minister’s Twitter thread.
The Tory minister told the BBC’s Today Show this morning: “Sentencing... has been fiendishly complicated and it’s very often frankly not understood even by people who are close to it.
“And I think it was right of the Prime Minister to explain in his tweet yesterday, which was a 16-parter, the timeline of the legislative changes so that we can fully understand the regime that this particular offender was sentenced under.”
The Conservatives were contacted this morning for a response.
Khan was shot dead by police after he fatally stabbed former University of Cambridge students Saskia Jones, 23, and Jack Merritt, 25, at a prisoner rehabilitation programme.
He had been released on licence in December 2018, midway through a 16-year prison sentence he was given after being convicted of terror offences.
Khan had been wearing an electronic tag when he started his attack at Fishmongers’ Hall, near Borough Market, having been invited there to attend a prisoner rehabilitation conference.
Since then, politicians and the media have focused on prisoner rehabilitation and sentencing.