A legal challenge against the UK government's controversial parliamentary deal with the Democratic Unionist Party is to be launched at the High Court.
Two judges in London will hear an application today by Northern Ireland resident and Green Party politician Ciaran McClean for permission to bring a judicial review of the legality of the £1bn deal.
Co Tyrone father-of three and mental health worker Mr McClean, who has raised thousands by crowdfunding for the legal action, accuses the UK Government of "buying DUP votes" to hold on to power.
The parliamentary deal - branded "shabby and reckless" by Labour - saw the DUP's 10 MPs agree to support the Conservatives' minority government in a series of key Westminster votes.
In exchange, Northern Ireland's largest party secured £1 billion of new Treasury investment in the North.
The deal struck in 10 Downing Street came after negotiations stretching 18 days following the June 8 General Election.
Under the "confidence and supply" arrangement intended to last until 2022, the DUP guaranteed that its MPs will vote with the government on the Queen's Speech, the Budget, and legislation relating to Brexit and national security.
Mr McClean is pursuing the case as a private individual and not in conjunction with the Green Party NI.
He will argue that the "money for votes" agreement breaches the Bribery Act 2010, and is a "corrupt bargain".
The DUP has insisted the Westminster arrangement will provide stability for the UK at a time of uncertainty while offering much-needed investment for the whole of Northern Ireland.
The UK government has consistently rejected any suggestion that its impartiality on Northern Ireland issues has been compromised, insisting that its role in political negotiations at Stormont is entirely separate from the House of Commons deal.
David Greene, a partner at London law firm Edwin Coe, which is representing Mr McClean, has said that nothing in the Government's case relating to the court action "dissuades us from concluding that the DUP agreement is corrupt and very simply unlawful".
The application will be heard by Lord Justice Sales and Mr Justice Lewis.