The High Court will later consider separate legal challenges from the Lib Dems and SNP over their exclusion from ITV’s general election debate.
Its head-to-head between Conservative leader Boris Johnson and Labour leader Jeremy Corbyn takes place on Tuesday.
But the SNP and Lib Dems say it is unfair not to invite them to take part.
The Lib Dems have also sent a legal letter to the BBC over its decision not to include leader Jo Swinson in a debate on 6 December.
The SNP said it expected the High Court to decide on Monday whether the two legal challenges should be heard together, and a ruling is expected later in the day.
Speaking ahead of the hearing, SNP Westminster leader Ian Blackford said the challenge was “about fairness for every voter and viewer across the country who have a right to see the real choice at this election”.
He added that it was “simply false to tell viewers in Scotland that that is their choice when we know Scotland has repeatedly rejected both in recent elections and the SNP could well hold the balance of power on 13 December”.
He told the BBC that “we may be in a minority government situation” after the general election so it would be “right” to hear the views of smaller parties.
The Lib Dems argue that the Conservatives and Labour are both pro-Brexit parties and it is wrong to exclude “a voice of Remain” – and the only female candidate for prime minister – from the head-to-head debates.
Sam Gyimah, the former Conservative minister who defected to the Lib Dems in September, said ITV was “colluding” with the two largest parties to “give them what they want”.
“The broadcasters are trying to work out what they think will make good television for their viewers,” he told Sky News. “It is wrong for broadcasters to pre-judge who will end up in Downing Street based on where we are 24 days away from the poll.”
When ITV announced its plans, the channel said it would hold a live interview-based programme alongside the leaders’ head-to-head to allow other parties to comment, as well as another multi-party debate ahead of the 12 December poll.
The Liberal Democrats have also criticised the BBC’s plan for a live head-to-head between Mr Johnson and Mr Corbyn on Friday, 6 December, because Jo Swinson is not taking part.
The party’s lawyers have sent a letter to the BBC’s director general Tony Hall, saying the exclusion of Ms Swinson is “clearly unlawful”.
“It also means that viewers will be denied the opportunity to hear the fresh and distinct perspective that the Liberal Democrats bring on the dominant issue of this election, namely Brexit,” the letter said.
The BBC declined to comment on the letter.
The broadcaster will host the live head-to-head debate between Mr Johnson and Mr Corbyn in Southampton on 6 December, plus a seven-way podium debate between senior figures from the UK’s major political parties on 29 November, live from Cardiff.
And BBC Scotland will stage a televised debate between the SNP, Conservatives, Labour and Liberal Democrats on 10 December, although the Scottish Greens have criticised the decision not to include them.