One of the gravest dangers to any society is “outrage fatigue”. The symptom of this condition is when so many people have been so angry for so long that terrible abuses of power now seem almost normal. Over a decade since the financial crash, after nine years of crippling public spending and tax cuts, and three years on from the bitterly fought EU referendum, poor leadership leaves our country in a state of polarised peril. This is frightening for people all over the United Kingdom, but it poses the biggest threat to the most vulnerable – and now to democracy itself.

The idea of shutting down parliament (no need to dress it up with the fancy language of prorogation) so that a hard-right, minority government can facilitate a “crash-out” Brexit on 31 October, was first suggested during the Conservative leadership campaign by Dominic Raab in June. Boris Johnson has refused to rule it out ever since. So last weekend’s reports of leaked emails between No 10 and the attorney general were hardly a bolt from the blue.

Whatever the nasty anti-politics, the analysis won’t wash under United Kingdom constitutional law

Yet, in the words of that fictional antithesis to Donald Trump, President Bartlet of The West Wing: “Is it possible to be astonished and, at the same time, not surprised?” When Jeremy Corbyn commissioned my formal advice on the subject, I felt able to produce it with complete confidence (for reasons I am about to explain). However, it was still a sobering task for someone who has always believed that in Britain at least, the overwhelming majority of MPs, however divided on almost everything else, share a respect for our representative democracy and the House of Commons in which they have the privilege to serve.

Since Johnson’s election (by 66% of the voters among a Tory selectorate of less than 160,000 members), the new prime minister and his advisers have made their ominous vision clear. Not for them, having to command the support of a Commons majority for their plan to deliver the nation and its world-envied health service into the hands of a grateful US president. The 2017 general election (that provides the mandate for most Labour MPs), means nothing to them. Instead, they see their authority to govern as derived from the result of the 2016 referendum alone. So their strategy is to pit parliament against “the people” with the great golden leader and his friends on the side of the latter. Others can consider which far-right play book they may be copying from. I will simply say that, whatever the nasty anti-politics, the analysis won’t wash under United Kingdom constitutional law.

The leading authority on the relationship between government and parliament (and prerogative and legislative power) comes from our Supreme Court as recently as 2017. The Miller case concerned whether prerogative power alone could be used to trigger article 50. Theresa May’s government argued that it was, and lost 8-3. However, importantly, all 11 justices were in total agreement that parliamentary sovereignty remains the foremost and overarching principle of our constitution. They were clear that the referendum result is a matter of enormous political significance but it does not change the law. The referendum only happened because of an Act of parliament and, under our system, no prime minister can govern without sufficient parliamentary support. If it was not permissible to trigger article 50 without the permission of parliament, it can hardly be acceptable to subject MPs to a “lock-out” to prevent them thwarting Johnson’s smash-and-grab plans.

To those who say: “I’m fed up with the lack of House of Commons agreement,” I understand the frustration and I am glad that opposition MPs have now sat down constructively with the leader of the opposition. I also believe that this latest contempt for our constitution will focus the minds of even previously ultra-loyal Conservative MPs. It isn’t just “no deal” that No 10 might get away with if “shut-downs” are now allowed. If “getting on with Brexit” is an excuse, why not shut down to deal with the social, economic and civil fall-out? Why not in times of war? The Commons met during the Blitz, even when the chamber had been bombed. Right or left, in or out, no one voted for this, and Johnson’s hero, Winston Churchill, must be spinning in his grave.

Yet No 10 now says that this is not the abusive suspension discussed over the summer. It is something different, a “bog-standard” break in advance of a Queen’s speech. No one is fooled. Every intemperate utterance blaming MPs sends the cat hurtling further out of the bag. If you want to subvert our British constitution, best not to spend so long telegraphing your intent.

• Lady Shami Chakrabarti is shadow attorney general for England and Wales