THE future of parliamentary democracy will be at stake this week when the UK’s highest court rules whether Boris Johnson’s suspension of Westminster was unlawful, campaigners have warned.

The battle over whether the shutdown of Parliament was done to prevent MPs challenging Brexit plans will culminate in the Supreme Court issuing its judgement on appeals from two separate challenges brought in England and Scotland.

Jo Maugham QC, who is fronting one of the actions along with SNP MP Joanna Cherry QC, told the Sunday National he was “quite confident” the court would find in favour of the argument that prorogation had been unlawful.

He said: “It was an amazing moment to stand outside the Supreme Court and say I expected the result of a hearing to be restoration of Parliamentary democracy in the United Kingdom.

“I don’t think it is any exaggeration to say that’s what was at stake – because Parliament cannot function in a world in which it can be suspended at any time for whatever motive and whatever period the Prime Minister chooses.

“That hollows out Parliamentary democracy to nothing, so it is a hugely significant case.”

The case, heard over three days before 11 judges last week, has been a historic test of the separation of powers between the Government, Parliaments and the courts – with the live stream on the first day accessed 4.4 million times.

Aidan O’Neill QC, representing a group of around 75 MPs and peers led by Maugham and Cherry, told the judges it was “the mother of parliaments closed down by the father of lies”.

The government’s lawyers argued it was “untenable” to accuse the Government of trying to obstruct Parliament and it was “forbidden territory” for judges to intervene on political arguments about its suspension.

Maugham added: “If the courts can’t go here on whether prorogation is lawful, then they can’t go to whether prorogation is lawful at any moment, and against any background.

“It is a really bold proposition and I think one the Supreme Court had profound difficulty with.”

Johnson will face a further legal challenge this week being spearheaded by Maugham and Cherry, which is trying to compel him to seek an article 50 extension,

The Court of Session will be asked to use a power known as nobile officium, which means it could send the request on Johnson’s behalf, if he refused to do so.

MPs passed a bill to block a No-Deal Brexit, which gives the Prime Minister until Saturday 19 October to pass a new Deal – or he will be forced to seek a three-month extension to Article 50.

But Johnson – who has staked his premiership on getting Britain out of the EU by 31 October on a “do or die” basis – has repeatedly suggested he will refuse to ask for a delay to Brexit.

Maugham said a submission had now been received from the Government on the case and he expected to find out tomorrow when the hearing is going to be, which is likely to be next week.

Dr Nick McKerrell, lecturer in constitutional law at Glasgow Caledonian University, said at the heart of the Supreme Court case was the issue of “deciding where power lies”.

He said: “In other countries in the world – and in Scotland in 2014 – if we had voted to become independent, one of the things which was said was we would develop a written constitution that would put these things in process.

“Britain does not have that, so the question arises if power is abused – as is argued is the case here – then who can stop that?”

Dr McKerrell said he believed it is more likely the Government will lose the case, as the view it was not a matter for the courts was “old-fashioned” and ignored the development of the process of judicial review of public bodies and other official decision makers.

He added: “Having said that, it would still be a massive thing for the court to overturn an action that has been done in the name of the Queen.”

If the judges do rule that the court has no place in interfering with purely political matters, then the suspension of Parliament will continue until October 14.

But if they decide that the prorogation was unlawful, then Parliament could be recalled.

Lord Keen QC, representing the Prime Minister, told the court Johnson will comply with the Supreme Court’s ruling if it concludes his advice to the Queen was unlawful –but refused to rule out the possibility he may advise the monarch to prorogue Parliament for a second time.

However Dr McKerrell said: “It would be very provocative to do that.”

Professor Amelia Hadfield, head of politics at the University of Surrey and director of think-tank the Centre for Britain and Europe, said there would be wider issues from a ruling in favour of the Government.

She said: “This is also going to drive a real wedge into the already fragile consensus between Westminster and Holyrood about their various attitudes towards governing Brexit and the role of Westminster.”

Hadfield pointed out if MPs do return to Parliament as a result of prorogation being ruled as unlawful, it could impact the plans for the Conservative party conference.

But she added: “Those who feel this is necessary will see it as a tremendous benefit with more time to debate Brexit. You can’t have closed doors – that is not how democracy works.”