SNP MPs went back to Westminster this week facing a fight against Tory plans to curtail the powers of the Scottish Parliament in order to create a post Brexit “internal market” in the UK. Sadly, this is unlikely to be a fight we can win at Westminster. Last year’s General Election delivered a huge majority for Boris Johnson and took away the leverage the SNP had in the previous hung parliament. But what’s done is done and whilst we cannot win the fight at Westminster, we can win it in the court of public opinion. The polls suggest this is already happening.

Ultimately most readers of this paper know that the only way to protect Scotland’s Parliament is by achieving our independence from Westminster rule. Winning more hearts and minds to that point of view is an important task and one to which SNP MPs can contribute, albeit that Holyrood will be the engine room in which the next independence referendum is delivered.

This week I led for the SNP on the first of a number of legalistic bills required as a consequence of Brexit. On this occasion, it was a bill to ensure Scotland and the UK continue to be part of international agreements regulating cross-border financial support and custody disputes in the field of family law.

This bill is relatively uncontroversial, and Holyrood has granted a Legislative Consent Motion. However, the Brexit process has told us that where Holyrood does not grant legislative consent the Tories are still prepared to go full steam ahead to deliver their programme, despite its rejection by the overwhelming majority of Scottish voters.

This is a big problem, particularly as it seems the fight over the post-Brexit internal market is not the only attempt to undermine the Scottish Parliament which we are likely to encounter. Quite separately from Brexit there is another potential threat looming not only to Holyrood’s powers but also to the independence of Scotland’s legal system.

At the end of July the Lord Chancellor, England’s Justice Secretary, announced an “Independent Review of Administrative Law”. The terms of reference make it pretty clear they are looking to “reform” the process of judicial review across the UK, ignoring Scotland’s separate and distinct legal system and the fact that the system of civil justice in Scotland is fully devolved.

Judicial review is the means by which the legality of Government actions and decisions can be challenged in the courts. Perhaps the best known recent example of a judicial review case is the prorogation case in which the UK Supreme Court ruled that the UK Government’s attempt to shut down parliament for six weeks was unlawful. However, judicial review is also used more routinely by litigants challenging Government decisions in the fields of immigration and asylum, housing, the environment and welfare. The WASPI women are currently challenging the unfair changes to state pension ages by way of judicial review.

The Government want to reduce or limit these cases so as to reduce scrutiny of their actions. Boris Johnson, Dominic Cummings and Michael Gove are still sore from the defeat inflicted upon them in the UK Supreme Court. Priti Patel and many Tory backbenchers are livid about the number of high-profile immigration cases raised by way of judicial review that they have lost since the turn of the year.

Last week official Government channels shared an animation of deportation flights leaving the UK, claiming that “activist lawyers” are delaying the removal of immigrants. But it is not the lawyers who are delaying the flights, it’s the courts and they would not do so unless they had found that the UK Government was acting unlawfully or outwith its powers.

LORD Faulks, a former Tory minister and now a crossbench peer, is to chair the review. His track record does not inspire confidence. He has advocated repeal of the Human Rights Act and a UK exit from the European Convention on Human Rights. He was also vocal in his disapproval of the Supreme Court’s unanimous ruling in the prorogation case. To ask us to see him as an impartial chair is an insult to our intelligence.

To understand why the UK Government are so keen to make sure that the scope for challenging their actions is the same north and south of the Border it is important to remember the significant influence the Scottish courts had on the outcome of the prorogation case. Two separate legal challenges were brought against the prorogation, one by Gina Miller in the English courts and the other in the Scottish courts by a group of MPs and peers led by me. At the first instance the English Divisional Court rejected Gina Miller’s challenge and it took three judges sitting in the Inner House of the Court of Session, Scotland’s Supreme Court, to breathe new life into the cases when they ruled that the prorogation was unlawful. Two weeks later, 11 UK Supreme Court judges unanimously followed the Scottish courts lead.

Make no mistake about it – that is why the Scottish courts are now in the UK Government’s sights. Where UK Government actions have implications across the UK, they can be challenged by litigants affected in either jurisdiction. If judicial review is curtailed in England, only then challenges could still take place in the Scottish courts.

However, the UK Government would be absolutely wrong to interfere with the scope for judicial review in Scotland.

Judicial review is part of our system of civil justice which is a devolved matter under the Scotland Act and therefore the preserve of the Scottish Parliament. Moreover, the authority and privileges of the Court of Session, including its inherent supervisory jurisdiction, are protected by Article 19 of the Treaty of Union which states “that the Court of Session or College of Justice do after the Union and notwithstanding thereof remain in all time coming within Scotland as it is now constituted by the Laws of that Kingdom and with the same Authority and Privileges as before the Union subject nevertheless to such Regulations for the better Administration of Justice as shall be made by the Parliament of Great Britain”.

LEGISLATION which sought to narrow the scope of the court’s powers and to curtail the right to judicial review could scarcely be described as “for the better administration of justice”.

It has been suggested that some parts of the Treaty of Union including Article 19 are so fundamental that the UK Parliament does not have the power to legislate in contravention of them, but that argument has never been definitively tested in court. If the Tories intend to attack the right to judicial review in Scotland, then this might be the opportunity to get a court to definitively answer this question. The outcome could have potential knock-on effects for the Union.

My fellow prorogation case litigant Jo Maugham QC has said it would be foolish for the UK Government to try to rewrite the Treaty of Union and undermine Scotland’s separate legal system at a time when Brexit has already delivered majority support for independence in the polls. Yet, on the face of it, that is just what the Tories intend to do. I have written to the Lord Chancellor outlining my concerns. His answer should make interesting reading. Watch this space.