The SNP is taking legal action against the BBC in an attempt to force the broadcaster to include the party in this week's final prime ministerial debate.
BBC Scotland political reporter Andrew Black answers some of the main questions behind the dispute.
What is the SNP's complaint?
The UK's three main broadcasters - ITV, the BBC and Sky, agreed to stage a series of prime ministerial debates featuring main party leaders
Gordon Brown, David Cameron and Nick Clegg.
SNP leader and Scottish First Minister Alex Salmond, who was not listed for inclusion in these programmes, has described the move as a "democratic disgrace".
Mr Salmond's critics point out he is not vying to become PM and, in fact, stood down as an MP in this election.
But the SNP leader argues that, as his party forms the Scottish government, its presence is crucial in the debates, which have discussed devolved issues such as health, justice and education.
How have things reached the stage of court action?
Mr Salmond started out by being prepared to be
flexible on the debate
Both he and Plaid Cymru leader Ieuan Wyn Jones had written to the BBC to argue their inclusion would be "proportionate and fair".
They also at the time suggested a fourth election debate should take place in either Scotland or Wales, which would address "topics of relevance" to viewers in the devolved nations.
The decision not to include Mr Salmond and Mr Jones in the main debate culminated in a complaint to
the BBC Trust, which ruled
it was "appropriate" to exclude them.
The trust added the SNP and Plaid would be represented at televised debates in Scotland and Wales respectively which were "clearly signposted" by the BBC.
The BBC also said only the Labour, Lib Dem and Conservative leaders could go on to become the next prime minister.
Following the trust's ruling, the SNP decided legal action was the only option.
Plaid Cymru supports the SNP's stance but will not take part in joint action, due to separate legal systems.
How is the legal action being paid for?
Following the trust's ruling, Mr Salmond said the SNP was unlikely to take legal action - the cost of which he had put at £70,000 - on cost grounds.
After all, as well as the UK election, the SNP will have to defend its status as Scotland's largest party in next year's Scottish Parliament election campaign.
At the weekend though, the SNP launched an appeal for donations to pay the legal bill, declaring it had hit its target to raise £50,000, through small contributions online from more than 1,600 donors.
The appeal was part-PR exercise - the party was hardly likely to issue a press release stating it had failed to hit its fund-raising target.
Why is the party going after the BBC in particular?
The SNP had grumbled about its non-inclusion in the first two debates staged by the commercial broadcasters.
However, the Nationalists argue the BBC has an "extra social responsibility", saying the corporation is the national broadcaster of Scotland as well as the UK, with millions of people living north of the Border paying the licence fee every year.
What outcome is the SNP hoping for?
The Nationalists say their case is straightforward - that it is "unfair and undemocratic" not to be allowed to participate.
The party insists is does not want to stop Thursday's final debate in Birmingham.
The SNP says its proposed action would seek to ensure the debate was broadcast in Scotland "with the nation's political make-up fairly reflected".
This would involve either having SNP representation in Thursday's debate or through an agreement to have a further "fair leaders' debate" organised before polling day.
What could the courts decide?
The SNP is raising its action at the Court of Session in Edinburgh and any decision is entirely in the hands of the judge or judges hearing the case.
The courts could rule the debate must be blocked from being shown in Scotland, thereby forcing the BBC Trust to review its decision - or the SNP's case could be dismissed altogether.
The SNP say there is legal precedent here - in 1995, opposition politicians won a court ruling which prevented the screening of a BBC Panorama interview with the then prime minister, John Major, in Scotland, where local authority elections were taking place at the time.
What do the other political parties have to say about all this?
They are not amused. Labour, the Conservatives and the Liberal Democrats all say Mr Salmond is only interested in grabbing headlines.
The parties say Mr Salmond was offered a space on four Scottish leaders' debates and refused three of them, only agreeing to the one staged by Sky TV.
They also say the SNP leader has been "completely unable" to explain why he refused to take part in a BBC Scotland debate on Sunday night, or why he was boycotting the main BBC Scotland election debate this weekend.
What happens next?
That's entirely in the hands of the court -
the SNP has lodged the legal papers
and is due to be heard by judge Lady Smith on Tuesday afternoon.