London - 19 September 2019

1. Various of exterior of Supreme Court

2. Gina Miller, transparency activist who took the government to court over the suspension of Parliament, arriving at court

3. Media

4. Cutaway of court entrance

5. Various of arrivals

6. Set up of Jeremy Brier barrister and legal commentator

7. SOUNDBITE (English) Jeremy Brier barrister and legal commentator:

"Well, today is day three at the Supreme Court in this Miller case, it's going to be absolutely fascinating because we've got the interveners so people who want to make submissions to the Supreme Court but aren't actually parties. Now, one of the interveners that's very headline grabbing if I can use that phrase is Sir John Major, the former Prime Minister of the United Kingdom. He is going to be saying that Boris Johnson's suspension of parliament was unlawful because it undermined parliamentary sovereignty."

8. Cutaway of Supreme Court sign

9. SOUNDBITE (English) Jeremy Brier barrister and legal commentator:

"Sir John Major himself once prorogued parliament in 1997 and was accused in that instance of having done it for improper political purposes, namely trying to avoid scrutiny for a cash for questions scandal. So we see an extraordinary dynamic."

10. Cutaway of Brier's hands

11. SOUNDBITE (English) Jeremy Brier barrister and legal commentator:

"In terms of court theatre, this is as significant and colourful as it gets. One prime minister, a Conservative prime minister, going into court to effectively argue through his counsel against a sitting Conservative Prime Minister saying what he has done is unlawful. The question of course is does this really impact on the 11 judges or is it more playing to the gallery at home?"

12. Cutaway of court wall

13. Various of artist holding up a painting of a caricature of Boris Johnson

Britain's Supreme Court has started its third and final day of a hearing into whether UK Prime Minister Boris Johnson acted lawfully in suspending Parliament just weeks before the UK is due to leave the European Union.

The judges are hearing two appeals, one by transparency campaigner Gina Miller's legal team and the other by the government appealing a Scottish court ruling that the decision was unlawful.

Judges at the country's top court will hear Thursday from a lawyer for former Prime Minister John Major, who is among those challenging the decision by Johnson, one of his successors as Conservative leader.

Opponents claim Johnson sent lawmakers home until October 14 to prevent them scrutinizing his plan to take Britain out of the EU at the end of next month, with or without a divorce deal. They also accuse the prime minister of misleading Queen Elizabeth II, whose formal approval was needed to suspend the legislature.

The government says the suspension is routine and not motivated by Brexit, and argues that judges should not interfere in politics.

The 11 Supreme Court justices are unlikely to give their judgment before Friday at the earliest. If the court rules that the suspension was illegal, Johnson could be forced to call lawmakers back to Parliament.

It would be a new blow for Johnson, who is battling to fulfil his pledge to lead Britain out of the EU on the scheduled date of October 31 come what may.