Geoffrey Cox was right.  The Commons would be wrong to demand – to pick an example he gave yesterday – to see “the papers of the secret intelligence service”.  M15 and MI6 would be unable to work in such circumstances.  One might as well send their files to ISIS, or to Vladimir Putin, or to Al Qaeda – or to our EU interlocuters in this Brexit negotiation, to pick a less adverserial but no less significant example.  There would be a vast difference between the limited information that the services provide to the Intelligence and Security Committee, and the supply of their entire, unredacted records to every single MP.

So it is, too, with a full account of what happens in government (for without some degree of confidentiality it couldn’t work coherently); with, in some circumstances, secret information on which British jobs and livelihoods depend; with documents about terror suspects or double agents, and so on.

The Attorney-General was also wrong.  Ultimately, the legislature must have its way – however foolish it may be.  The Executive cannot simply dismiss its authority and pray in aid a higher one.  We fought a civil war over the matter and the principle is settled.  The divine right of Kings cannot be succeeded by the divine right of Ministers.  That may be an over-dramatised way of interpreting what Cox yesterday called “the public interest…the national interest”.  But Ministers cannot be allowed to determine what this is for themselves – unchecked, unquestioned, unrestrained.

Under normal circumstances, the unwritten conventions apply.  The legislature doesn’t make foolish demands.  And the executive bows to the legislature.  But these are not normal circumstances.

What is happening is that the conventions are being stretched to breaking point by, on the one hand, a referendum decision to leave the EU, delivered by a record number of voters and endorsed by the manifestos of both main parties at last year’s election; and, on the other, a Commons increasingly emboldened to resist that decision.  We have, at least in possible outline, a Leave electorate v Remain MPs; Parliament v the people.  And between the two, a torn, conflicted and weak Government (faced by a opportunistic, self-contradicting and divided Opposition).

Cox’s appearance yesterday was a symptom of the breakdown.  The Attorney usually cloaks his function as an operating politician beneath his other function as law officer. He seeks to presents himself as a dispassionate figure – not one caught up in the emotions of debate.

Cox found this impossible yesterday, and so spoke as he did: “the truth is that I am caught in an acute clash of constitutional principle,” he told the Commons.  Similarly, we cannot remember a Minister whose core argument to the House was: “I admit that my case is flawed.  But it is on balance a lesser evil than the alternative, in my judgement – though others might reach a different conclusion”.  The usual approach is to suggest that the Government is right about everything and the Opposition is wrong about everything.

Finally, in these Trumpian and Cadwalladrian times, one’s opponents must, naturally, be slagged off at best (however untruthfully) and declared guilty of conspiracy at worst (whatever the quality of the evidence).  So it is that some of our fellow Brexiteers will believe the Attorney-General’s full legal advice to conceal some hideous smoking gun.  But it is hard to believe that any weapon could smoke more noisomely than his candid admission yesterday that we will have no unilateral right to leave the backstop if May’s deal is approved.  Often the key facts are in plain sight before our eyes.

One old friend of ConservativeHome told us today that he wouldn’t vote for today’s motion to hold Ministers in contempt, because that would imply that Cox’s concerns are unreasonable.  And that he wouldn’t vote against it, because that would suggest that the Executive must have its way.  Abstention is never desirable. But we see what our friend is getting at.