Case Study:Joanna Cherry/Gina Miller case 2019

In August 2019,  then prime minister, Boris Johnson, announced that he had decided to prorogue (suspend) Parliament for 5 weeks that autumn. Prime ministers possess this right. However, the length of time that Parliament would not be sitting caused accusations that the prime minister wanted to limit parliamentary opposition to his EU withdrawal proposals and so his actions were motivated by political self-interest, so while this power existed it was being used in a highly unusual way and since the UK has no codified constitution it could be argued that the PM's action exceeded his powers.

As a result, Gina Miller and the SNP MP Joanna Cherry brought two cases against the prime minister alleging that the government was illegally seeking to limit Parliament’s sovereign right to hold the government to account. Gina Miller initially lost her case at the High Court, but in Scotland Joanna Cherry’s case was upheld.

Consequently, both cases were appealed to the Supreme Court to determine the meaning of the law. On 24 September, the 11 justices hearing the case unanimously found that the prime minister had acted illegally by suspending Parliament for such an excessively long time when momentous constitutional issues needed to be fully debated.

In her judgment, Lady Hale, the then president of the Supreme Court, stated, ‘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.’ Consequently, ‘It is for Parliament, and in particular the Speaker and the Lord Speaker, to decide what to do next. Unless there is some parliamentary rule of which we are unaware, they can take immediate steps to enable each house to meet as soon as possible.’

On 24 September 2019, in a unanimous decision by eleven justices, the court found that the matter was justiciable, and that Johnson's advice was unlawful; this upheld the ruling of the Inner House of the Court of Session in Cherry, and overturned the High Court of Justice's ruling in Miller. As a result, the Order in Council permitting the prorogation was null and of no effect and Parliament had, in fact, not been prorogued. 

According to Gina Miller, the judgment represented ‘a win for parliamentary sovereignty’ since it legally confirmed that the prime minister had improperly used the royal prerogative when attempting to prorogue Parliament.