Julian Brazier is the Conservative MP for Canterbury.

It is widely agreed that war should not be left to generals and (at least since 2008) that banking should not be left to bankers. We need the late, great Parliamentarian Sir Robin Maxwell-Hyslop back to remind us that the Law should not be left to lawyers.

A terror to ministers of governments of both hues, Robin believed strongly in the independence of the judiciary. But the point of his dictum was that, under Britain’s uncodified constitution, it is Parliament, not any court, which is the guardian of the constitution.

Using his formidable understanding of the orders and customs of both houses, he sank the Callaghan government’s flagship nationalisation measure by getting a ruling from the Speaker that the bill had followed the wrong Parliamentary procedure.

When the government disgracefully used its majority to brush aside the Speaker, Michael Heseltine leaped up and brandished the Commons mace. But using this ruling, the industry was able to petition the House of Lords. Crucially the matter was dealt with by an ad hoc committee of that House, not its judicial sub-committee (which Tony Blair converted by sleight of hand into our present ‘Supreme Court’). A young lawyer called Bill Cash appeared for the appellants and the rest is history.

The Article 50 case before the Supreme Court, and the threat of further legal actions over Brexit, illustrate the muddle developing in our legal system. There is a growing proportion of lawyers who simply do not accept that – in Britain – there are constitutional matters, involving the workings of Parliament and its relationship to the government, which the courts have no sway over.

In America, with her codified constitution, the Supreme Court is just that: supreme. It has the final say on interpreting the constitution. That is why there has to be careful political scrutiny of appointments to it. In this context, the recent much-alluded to lecture by Baroness Hale contains an important passage:

“This does, of course, illustrate the gaping hole in the power of the Supreme Court of the United Kingdom to act as guardian of the UK Constitution in the same way that other Supreme and Constitutional courts do the world over. We cannot strike down Acts of the UK Parliament. But please do not think that I – or any of my brethren – want us to be able to do that.”

This does recognise some limit to the powers of the Supreme Court, by accepting that it cannot ‘strike down’ Acts of Parliament. But, more important is that a Supreme Court Judge is specifically claiming that that court is the ‘guardian of the UK Constitution’. That would come as news to generations of Parliamentarians.

The fact that Lady Hale delivered her lecture just before she was to hear the Article 50 case was widely attacked – and its ill-judged timing was recognised by Lord Mance’s decision to cancel a subsequent planned lecture.

But that is not the main point; what matters is that a judge of the Supreme Court has made a large and dangerous claim; her lecture repeatedly played lip service to our unwritten constitution but this quote summarises the extent to which she arrogates to her institution much which belongs to Parliament.

To see why this is so important, we need to remember what we mean by a codified constitution. In Britain there is no separation of powers. The Government is in Parliament and the relationships between the parts of Parliament and Government – and the courts themselves – largely fall outside Acts of Parliament.

For example, the requirement for a ‘long title’ on a bill prevents groups of Members from congressional-style ambushes on irrelevant pieces of legislation. No act of Parliament is involved. Commons Standing Orders define long titles and their application is determined by precedent, guarded carefully by the Clerks of both Houses.

Of the few constitutional Acts which do exist, the 1911 Parliament Act is probably the best known. Yet its statutory provisions are used rarely: annually in the case of the Finance Bill and just four times in over a century for overriding the upper chamber. In contrast, the informal practice which accompanied the 1911 settlement is used almost every week, policed by Parliamentarians and the clerks, not the courts.

If the Supreme Court curtails the ancient Royal Prerogative to sign treaties, the consequences for government will be serious. In a dangerous world, it will have implications, for example, for the use of military power. This, has always been understood to be a constitutional power of the Executive – but one where it Parliament rightly demands to be consulted as soon as is practical.

That arrangement – policed by Parliament, not the courts – served us well in both World Wars. Delays associated with undermining it could literally mean the difference between life and death.

The Lisbon Treaty dramatically changed our relationship with our European partners and ourselves. Inevitably some of its changes affected the rights of individuals. Its precursor, the proposed new constitution, was thrown out by referendums in France and Holland. So Brussels reintroduced that constitution through the backdoor as a treaty. Britain’s last Labour government signed up to it without either the referendum the Conservatives called for or – crucially – an Act of Parliament.

From a legal standpoint, this is irrelevant. Nobody brought a case. From a constitutional standpoint it is pivotal. Nobody brought a case because, despite the fury the measure introduced in Parliament, press and public opinion, the Government’s use of the power of the Royal Prerogative to sign the treaty was seen as unassailable.

Finally, to the aspect of all of this most likely to have reached the casual reader: Lady Neuberger’s tweets against Brexit. I believe the popular press were wrong on this, even though the Guide to Judicial Conduct is explicit: ‘Where a close member of a judge’s family is politically active, the judge needs to bear in mind the possibility that, in some proceedings, that political activity might raise concerns about the judge’s own impartiality.’

Lord Neuberger has the reputation for integrity typical of a holder of his post. If the Neuberger household had deliberately flouted the judicial code forty times, he should have resiled. The reason he has not done so, I believe, is not that he was ignorant of his wife’s actions nor that he despises the code but simply that, during the referendum campaign, it never crossed his mind that this case would come before him. That has no legal significance, of course, but is a constitutional elephant.