Boris Johnson had no legal precedent

The argument

The case for illegality begins with how far outside precedent the decision fell. Boris Johnson's move to prorogue parliament on 12 September 2019 was, on this argument, unprecedented in British political history: the new parliament would not start until 14 October, a full 33 days after the previous parliament ended. Not since 1931 had a parliament been prorogued for 33 days, and since the turn of the millennium the average length of time between parliamentary sessions had been eight calendar days. The length is what carries the weight. A prorogation of a few days is a procedural formality; one of 33 days removes the legislature from the field for a stretch with no modern parallel. The step from unprecedented to unlawful is supplied by the nature of the British constitution. Because that constitution is not a written, codified document, there is no statute to point to setting out how long a prorogation may last or what a prime minister may use the power for. What governs parliament and prime minister instead is convention: settled practice, observed because it has been observed, which is the only thing giving the arrangement its shape. On this view convention is not decoration around the law but occupies the place that written rules occupy in other systems, and its authority depends entirely on being adhered to. That is why proponents treat the break with convention as more than a departure from custom. In a constitution made of convention, a prime minister acting far outside established practice is not exercising a lawful power in an unusual way but acting where no authority has been established; any breach of convention must therefore be seen as an unlawful act. Johnson having had no precedent for a prorogation of this length, his prorogation of parliament was unlawful.

Context

Boris Johnson’s prorogation is far longer than any that preceded it, leaving it without legal precedent.

Premises

Counter-arguments

The parliamentary session running from June 21, 2017, to September 9, 2019, was the longest on record. It ran for 810 calendar days. To allow it to continue would have defied precedent and pushed parliament further into unchartered waters. If, as Johnson's critics claim, convention is essential to the functioning of government, then they should celebrate the prorogation, not criticise it. Secondly, the length of the prorogation was also not unprecedented. Much of the period between sessions was already covered by the three-week parliamentary recess already planned for the party conferences. If you take this into account, the actual length of the prorogation was only seven days, not 33. This is a perfectly normal period of time to have between parliamentary sessions.

Rejecting the premises

[Rejecting P2] Boris Johnson's prorogation was not a breach of convention.