Boris Johnson news: Government lawyer refuses to say whether PM could suspend parliament again, as Supreme Court hears he 'committed worst abuse of power in decades'

A Liberal Democrat government would put happiness at the heart of its agenda, with every spending decision and every new law subjected to assessment of its impact on public “well-being”, Jo Swinson has announced.

The party would publish “well-being budgets” as part of the chancellor’s annual budget statement, and would create an official well-being watchdog to determine how the government’s actions were affecting happiness, said the Lib Dem leader.

Aides said she would consider appointing a “happiness minister” to oversee the process.

More here from our political editor Andrew Woodcock:

Gina Miller has left the Supreme Court after Tuesday's hearing, to cheers and boos from anti and pro-Brexit supporters respectively.

She was briefly followed from the door of the court by photographers and a handful of pro-Brexit demonstrators, one of whom shouted "traitor" after her.

The case continues tomorrow.

Meanwhile, Labour bosses have been accused of a “stitch up” to block an attempt by activists to force the party to close all detention centres.

Motions for next week’s annual conference urge Labour to beef up its existing policy of shutting down only the most notorious institutions – Yarl’s Wood and Brook House.

But they have been deliberately separated into two different subject groupings to, it is alleged, prevent them winning the race to be debated in a “priorities ballot”.

Our deputy political editor Rob Merrick has more:

UKIP leader Richard Braine has apparently decided to boycott his party's conference due to poor ticket sales.

Jo Swinson's first conference speech as Lib Dem leader received warm praise from senior party members, with Tim Farron describing her as "genuinely a credible alternative prime minister".

Ex-leader Mr Farron said: "I thought it was a great flowing speech that covered a wide range of things and offered a new alternative for the UK about more than just Brexit.

"My sense is that the Liberal Democrats have had opportunities over time, this is more than an opportunity, this is a duty.

"If the country is faced with a choice between hard-left socialism and populist English nationalism that's an appalling choice and we need to step into that space and we're very, very lucky that we have a leader who is doing just that, who is genuinely a credible alternative prime minister."

Lib Dem MP Dr Sarah Wollaston, a former Tory, said Ms Swinson's conference speech set out a "vision beyond the issue of Brexit" including wellbeing.

Ex-Labour MP Luciana Berger said she sat "proudly" listening to Ms Swinson's speech, adding: "It's something that I believe in and it's something that I want to go out and champion."

She said of the speech: "I thought it was fantastic, it was full of energy, it was ambitious as it should be, it challenged the other parties, it put forward some really exciting proposals for the country going forward which looked beyond Brexit."

Irish deputy premier Simon Coveney has said the UK government has still not put forward any written proposals on alternatives to the controversial Irish border backstop.

"We in the EU are open to a deal but it must achieve the aims of the backstop through a legally operable solution," he said.

"We await written proposals from the UK side. We simply haven't seen any written proposals to date."

The tanaiste said: "Just because Boris Johnson says the backstop needs to go, doesn't meant everyone else will respond positively to that because we know the consequences of a no-deal Brexit are significant and pose huge challenges for Ireland, north and south.

"There is an obligation on the party looking for change to come up with solutions that can deal with the consequences of what they are asking for. If that question can't be answered, we will not have a deal.

"If the current position from the UK side is that the backstop needs to be removed then it is a perfectly reasonable request by us to say that creates huge problems and how are you going to solve it and what are you going to replace it with?" said Mr Coveney.

Missed any of the action from today's Supreme Court hearing? Our political correspondent Ben Kentish has got you covered with a colourful write-through of the day's events.

Read his piece here:

The Indy's John Rentoulhas picked out the six key things from Liberal Democrat leader Jo Swinson's first party conference speech.

Can the Liberal Democrats turn momentum into votes? Swinson knows her party needs a distinct Brexit message to steal Remain votes from Labour in an early election.

Read our analysis here:

That's it for The Independent's politics liveblog for the day. Thanks for following!