ITV is hosting a head-to-head debate between Boris Johnson and Jeremy Corbyn on Tuesday, which will not include any other party leaders.
The Lib Dems and the SNP will contest the decision to exclude their party leaders from the debate at a High Court hearing in London on Monday.
Speaking ahead of the case, SNP Westminster leader Ian Blackford, who plans to attend the hearing, said: "This challenge is not just about the SNP, it's about fairness for every voter and viewer across the country who have a right to see the real choice at this election on that debate stage.
"By excluding key parties from the debate, viewers are being deprived of the opportunity to make their own decisions, and voters in Scotland are not seeing their voting patterns reflected at all.
"People in Scotland voted Remain in 2016 and overwhelmingly backed the SNP as their party of choice in the European elections.
"Polls show around 50% of voters support independence and more than that back Scotland's right to choose our own future.
"These key positions at the election won't be heard on that platform if the SNP is not represented.
"Labour and the Tories have not been the leading parties in Scotland at an election for around a decade, while the SNP has grown to become the third party in UK wide politics.
"It is 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 the 13th December.
"For those who want to support our call for fairness, not just for the SNP but for all parties, there is still an opportunity to donate to this case and to back a debate that gives the viewer and the voter what they want."