Prorogative power 'expressly preserved by Parliament'
The government's lawyer, Sir James Eadie QC, has argued that the decision to suspend Parliament is not one for the court to decide on.
At the Supreme Court he said that prorogative power had been "expressly preserved by Parliament" and that outside of "specific legislative control in particular context... the prorogative power is not subject to legislative control".
Critics have accused the PM of trying to stop the scrutiny of MPs in the run-up to Brexit on 31 October.
The PM suspended - or prorogued - Parliament for five weeks earlier this month, saying it would allow him to hold a Queen's Speech on 14 October to outline his new policies.