The political ramifications of Nicola Sturgeon's announcement of her intention to resign as Scotland's First Minister continue to play out.
Meantime, we explain some of the legal and constitutional issues that arise when there is a change of First Minister.
When can, and when must, a First Minister resign?
Unlike the position with the UK Prime Minister, the appointment and resignation of whom is a matter of constitutional convention, the Scottish First Minister's role and terms of appointment are governed to a much greater extent by law.
In terms of section 45 of the Scotland Act 1998 the First Minister may voluntarily tender their resignation at any time in office. Resignation is tendered by way of a letter to the King and while the King is not expressly required to accept the resignation he may be said to have a constitutional obligation to do so.
Commentators have noted that Nicola Sturgeon has resigned at a moment of her choosing. A First Minister can be compelled to resign and must do so if the Scottish Parliament formally resolves that the Scottish Government no longer enjoys the confidence of the Parliament. In such circumstances all Scottish Government ministers (including junior ministers) are also obliged to resign.
The legal effect of a resignation – and why Nicola Sturgeon has not yet resigned
When a First Minister is compelled to resign because there has been a vote of no confidence in the Government the resignation is presumed to have immediate effect. It is less clear whether a voluntary resignation also has immediate effect or whether a period of 'notice' can be given. This matters because once a resignation is formally tendered a 28-day period is triggered under section 46 of the 1998 Act during which a new First Minister must be nominated by the Scottish Parliament, which failing a general election must be held.
Where a resignation requires a temporary replacement to be installed, First Ministerial functions can be exercised by an Acting First Minister designed by the Presiding Officer of the Scottish Parliament.
Nicola Sturgeon's statement that she is remaining in office until her successor is appointed will be intended to avoid any problems this tight timeline may cause by slowing down the process and allowing time for the process of selecting a new leader of the SNP to take place.
First Ministerial functions
Whilst the First Minister may exercise any of the functions conferred on the Scottish Ministers by the 1998 Act, there are certain functions that are exercisable by the First Minister alone. These include the appointment and removal of members of the Scottish Government (including Scottish Ministers and Junior Scottish Ministers) and recommendations to the Prime Minister for appointments to the judicial roles of Lord President and Lord Justice Clerk.
These functions are expressly exempted from the doctrine of collective responsibility by the Scottish Ministerial Code.