It is far too early to tell to what degree the Government's options have been constrained. A key part of the adviceadvice is paragraph 50;
- For the purposes of the present case, therefore, the relevant limit upon the power to prorogue can be expressed in this way: that a decision to prorogue Parliament (or to advise the monarch to prorogue Parliament) 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 such a situation, the court will intervene if the effect is sufficiently serious to justify such an exceptional course.
The prorogation would be lawful with a reasonable justification. No such justification was given this time. Whether any justification a government may provide in future is reasonable is pure speculation at this point.
Later in the judgement, we see that;
- The unchallenged evidence of Sir John Major is clear. The work on the Queen’s Speech varies according to the size of the programme. But a typical time is four to six days.
It seems likely that a prorogation of longer than this period would need a very clear justification to avoid a legal challenge at a minimum.