Thread by @Raphael_Hogarth

This is a 900-word summary of what happened in the Supreme Court yesterday, for anyone who is catching up in order to follow today.

Probably more detailed than what you'll read in the papers, but hopefully more accessible than listening to 5 hours of submissions.
1/

Lord Pannick QC, for the challengers in England, made 3 main points.

First: the PM prorogued for 5 weeks in order to avoid parliamentary opposition to his policies.
2/

To support this, Lord Pannick said
- look at the PM's quotes (eg below)
- if the prorogation was just for a new Queen's Speech, as the PM claims, why was it so long?
- also, if the prorogation was just for a new QS, why didn't the PM want to make a witness statement saying so?
3/

Second, Lord Pannick said that executive power may only be lawfully exercised for proper purposes, and that avoiding parliamentary opposition is an improper purpose.
4/

To support this, Lord Pannick cited cases where the courts have looked at powers given to ministers by a statute, deciding what the power authorises the minister to do, and what the power does not authorise the minister to do (the "scope" of the power).
5/

In those cases, Lord Pannick argued, the court interprets the power, and what the "proper purposes" for which it can be used, in light of a more general constitutional background and principles of constitutional law.
6/

The power to advise HMQ to prorogue is not given by statute, but exists under the royal prerogative. So there is no textual starting point for defining the power's scope, Lord Pannick said. But that doesn't mean it can't still be limited by constitutional principles.
6/

The general constitutional doctrine here is that of parliamentary sovereignty. That should be understood broadly, Lord Pannick argued - it means not just the legal status of Acts of Parliament, but Parliament's role in the constitution as "senior partner", scrutineer, etc
7/

The essence of the argument, then, is that the PM's "purpose" of avoiding parliamentary scrutiny was inconsistent with the legal doctrine of parliamentary sovereignty, properly understood. That is why the prorogation, said Lord Pannick, was unlawful.
8/

Thirdly and finally, Lord Pannick argued that prorogation is justiciable: that there are legal standards against which the legitimacy of the PM's decision may be judged.
9/

To support this, Lord Pannick appealed to the idea of the rule of law. If the case raises a public law issue, he said, than the court can adjudicate on it. The doctrine that prerogative powers are non-justiciable has faded over time, he said.
10/

Parliament's job is to hold the PM to account for whether he exercises his powers in a politically acceptable way. The court looks at whether he exercises his powers *lawfully*.

If this prorogation is non-justiciable, he warned, a 1-year prorogation would be.
11/

In the afternoon, Lord Keen made submissions for the Government.

First, he criticised the *remedy* given by the Scottish court, which declared the prorogation unlawful and "null and of no effect".
12/

The court was not entitled to do that, he said, because part of the process of prorogation takes place in Parliament, and under Article IX of the Bill of Rights, proceedings in Parliament shall not be questioned in court.
13/

Instead, he said, if the prorogation were found unlawful, then the PM undertook to call Parliament back as a result. So the prorogation would have happened and a new session would start. He was asked whether the PM might then prorogue again. He said that's for the PM.
14/

Second, Lord Keen discussed the court's ability to adjudicate. It is well established than prorogation can be for political purposes, he said. The court is not well equipped to choose between valid political purposes and invalid ones: they are all political.
15/

To apply the doctrine of "proper purpose", he said, the court needed to be interpreting a statutory power, so it can ask: for what purpose did Parliament intend this power to be used? The power to advise prorogation is not a power under statute, but the prerogative.
16/

He then looked at the facts. Mostly, the law will be tackled by James Eadie, a different government lawyer, today.

Internal gvt documents, he said, show that this was not about avoiding scrutiny - and the lack of a witness statement was not relied on by the Scottish court.
17/

He was asked why the prorogation was so long if it was just for a Queen's speech. He said that it was because Parliament was expected to take a party conference recess over the summer anyway, so the number of lost sitting days would be small.
18/

The Scottish court was incorrect, Lord Keen said, to say that Parliament can call itself back from a recess but not from a prorogation. The House of Commons can call itself back from neither: only the PM (in the former case, with the agreement of the Speaker) can do so.
19/

He also noted that, if Parliament had wanted to limit the Government's powers to prorogue over the summer, it could have legislated to do so before the prorogation. Given that it didn't, he said, it is not for the court to step in.
20/

Today we hear form Sir James Eadie QC on the Government's legal arguments. We also hear from Aidan O'Neill QC, who is representing the parties who mounted their challenge in the Scottish courts.
/ends