Robert Buckland is facing a Gina Miller-style legal action by an Oxford University professor that alleges he has broken his statutory duty to uphold the law over Brexit.
The move, backed by one of Britain’s top constitutional lawyers and a former Treasury counsel, could force his resignation as Lord Chancellor if upheld by the courts.
It threatens to spark a new row between the Government and “activist” lawyers. David Greene, the new president of the Law Society and a major critic of ministers’ assaults on “leftie” lawyers, has previously been involved in the case but has stepped aside due to his new role and potential conflict of interest.
But defending the rights of lawyers to hold the Government to account, Mr Greene told The Daily Telegraph: “We have deep concerns about references to activist or leftie lawyers doing their job which is to interpret the law as made by Parliament. They are doing no more or less than that.”
The legal challenge against Mr Buckland is being mounted by Professor Joshua Silver, an Oxford University physicist who invented self-correctable lenses, and is being led by Khawar Qureshi QC, a constitutional expert and former Treasury counsel.
They claim that Mr Buckland, a QC, has failed to comply with his statutory duty as Lord Chancellor to respect the law over the internal market bill under which the UK reserves the right to break international law.
In a letter to Mr Buckland, they cited his “apparent inaction” in failing to advise the Government not to break law, his “connivance” in a potential breach of the law by voting for the bill, and his indication he would only resign if the Government broke the law “in a way [he] found unacceptable.”
They said these “all give rise to serious concerns that the Lord Chancellor breached (and continues to breach) his constitutional and statutory duty.”
They have given Mr Buckland until November 4 to respond – and will then decide whether to proceed with a judicial review that would make his position “untenable” if it found him to have breached his statutory duty.
Tory and legal sources claimed it was a “frivolous” politically-motivated move and pointed to previous action by Professor Silver who reported then Home Secretary Amber Rudd to West Midlands Police for a hate crime while giving her speech to the Tory party conference.
One source claimed Mr Greene’s involvement in the case was “highly inappropriate” and “brazenly partisan” as then vice president of the Law Society.
But Professor Silver said: “It seems to me that the present Government is now violating the rule of law. I am naturally hopeful the Government will acknowledge it is making a mistake, and change its course before its conduct has to be examined by the Courts.”
The bill gives the Government the powers to change the Brexit departure deal in potential breach of international law. Two Government law officers resigned in protest: Sir Jonathan Jones, the Treasury solicitor, and Lord Keen, the UK’s law officer for Scotland.
After a Tory revolt, ministers agreed an amendment that it could only use the powers to change the Brexit departure deal with prior approval of MPs.
Mr Greene – who also advised on the article 50 case against the Government – said he did not personally deal with the case although his firm did. It had now been taken on by another firm.
A spokesman for Mr Buckland declined to comment.