High Court judges will hear a legal challenge against ITV over an election debate that excludes the Liberal Democrat and SNP leaders.
ITV is hosting a head-to-head debate between Boris Johnson and Jeremy Corbyn on Tuesday, which will not include any other party leaders. Later on Tuesday evening, ITV will broadcast a series of interviews with other party leaders.
The Lib Dems and the SNP will contest the decision to exclude their party leaders from the debate at a hearing in London on Monday.
Lib Dem representatives lodged papers at the court in London last week and said it was "vital for our democracy" to have both sides of the Brexit debate included in TV debates during the election campaign.
Speaking outside the Royal Courts of Justice, party president Sal Brinton said: "General elections are about people's democratic choices.
"The TV debates offer the only chance for people to see how leaders compare to each other directly, in a neutral, equal and balanced format.
"For many people, this is the moment they decide how they will vote.
"Right now, most voters see Brexit as the single biggest issue for the country and the central issue for this election.
"And people know more about where they stand on Brexit than which party they will vote for.
"So it is vital for our democracy to have both sides of the Brexit debate represented at the top table of the leaders' debates."
Scottish First Minister Ms Sturgeon said last week that it is "fundamentally unfair" for other parties to be cut out of the debate.
She said: "This election may be the most important of our lifetimes. It is quite simply unacceptable for the SNP and other parties to be cut out of proposed leaders' debates by broadcasters.
"This is fundamentally unfair and it fails to recognise that the UK is no longer a two-party state.
"And in Scotland, this would not be a debate between the two leading parties - instead it would ignore the country's largest party, which according to the latest polls is also on track to win the third largest number of seats UK-wide.
"By contrast, the latest polls show Labour in fourth place in Scotland."
Sky News has proposed a November 28 date for its debate, while the BBC has confirmed it will host two debates, on November 29 and December 6, in addition to a series of Question Time specials.
The hearing, before Lord Justice Davis and Mr Justice Warby, is due to start at 10.15am.
- Johnson v Corbyn: The ITV Debate will be broadcast at 8pm on Tuesday 19 November, with the ITV Election Interviews broadcast at 10pm.