Since the UK Supreme Court has ruled that the proroguing of the UK Parliament was illegal, is Boris Johnson personally culpable? Does this depend on whether the UK Parliament and its democratic representatives reconvene themselves? If it is reliant on their reconvening, does the criminality or non-criminality of Boris Johnson or other related parties depend on who took what action, and when and why? Details very useful here.

IANAL, but probably the only thing he could be charged with is misconduct in public office. I haven't seen anyone suggest that he should be charged (for this, this time).

The charge does not require one to break some explicit statue. It also applies "where there is no relevant statutory offence, but the behaviour or the circumstances are such that they should nevertheless be treated as criminal". The criteria are:

• a public officer acting as such;


• wilfully neglects to perform his duty and/or wilfully misconducts himself;


• to such a degree as to amount to an abuse of the public's trust in the office holder;


• without reasonable excuse or justification.

However, last time Johnson was charged with this offence, by a private prosecutor, and for some political statements, it failed fairly quickly, when the granting of summons was appealed to the High Court.

Of course, the circumstances this time involve more than a statement, but insofar I haven't seen suggestions that he should be charged.

I don't know if the following argument meets all the legal criteria to be a good defence, but conceptually at least, the fact that the High Court of England ruled in favor of Johnson's government, could be used as an argument that "hey, it wasn't obviously unlawful before the Supreme Court decided so", i.e. this could be a valid excuse under bullet #4 from the criteria above.

No.

https://www.bbc.com/news/uk-politics-49810261

The notion of unlawful here means only that the prorogation does not comply with how the supreme court interprets the political rule book.

It doesn't actually mean any actual law was broken, or anything criminal occurred.

It is no different than saying, a law is unconstitutional. legislators who draft laws deemed unconstitutional by the US Supreme Court (which happens all the time) never face criminal charges. Because unconstitutional there only means it doesn't follow how the court interprets the constitution.

While this is a small difference, the supreme court found that the prorogation was unlawful rather than illegal. This may seem pedantic, but the law is often so. Boris will not be charged with a crime, because there is no crime to charge him with.

It is possible that he will break a law over this, but until he has done so it is impossible for charges to be brought.

Yes, but only if he tried the same thing twice

The courts of law are unlikely to rule this matter criminal in the first instance. However, if Boris Johnson were to try the same thing again, or were to attempt to disrupt the reconvening of parliament, he likely would be found in contempt of court, which is a criminal offense.

Highly unlikely

Most high courts (regardless of country) prefer to keep themselves out of the political process. When cases like this come up, they want to tailor things as narrowly as possible as to the question before them. In this case, the UK Supreme Court said this (trimmed for relevance)

The power to prorogue is limited by the constitutional
principles with which it would otherwise conflict. For present purposes, the relevant limit on the power to prorogue is this: that a decision to prorogue (or advise the monarch to prorogue) will be unlawful if the prorogation has the effect of frustrating or preventing, without reasonable justification, the ability of Parliament to carry out its constitutional functions as a legislature and as the body responsible for the supervision of the executive. In judging any justification which might be put forward, the court must of course be sensitive to the responsibilities and experience of the Prime Minister and proceed with appropriate caution.

If the prorogation does have that effect, without reasonable justification, there is no need for the court to consider whether the Prime Minister’s motive or purpose was unlawful

The third question, therefore, is whether this prorogation did have the effect of frustrating or preventing the ability of Parliament to carry out its constitutional functions without reasonable justification. This was not a normal prorogation in the run-up to a Queen’s Speech.

No justification for taking action with such an extreme effect has been put before the court.

The Court is bound to conclude, therefore, that the decision to advise Her Majesty to prorogue Parliament was unlawful because it had the effect of frustrating or preventing the ability of Parliament to carry out its constitutional functions without reasonable justification.

This Court has already concluded that the Prime Minister’s advice to Her Majesty was unlawful, void and of no effect. This means that the Order in Council to which it led was also unlawful, void and of no effect and should be quashed. This means that when the Royal Commissioners walked into the House of Lords it was as if they walked in with a blank sheet of paper. The prorogation was also void and of no effect. Parliament has not been prorogued. This is the unanimous judgment of all 11 Justices

The question here was one of procedure. Trying to make this criminal would create all sorts of chaos. What laws would he be guilty of breaking? What sentence should be carried out? Could the Supreme Court have all of Parliament arrested for violating parliamentary procedures

TL;DR

The High Court nullified the order to prorogue. It did not accuse Mr. Johnson of having committed a crime, only having broken the procedures of Parliament.