Lawyers for Denis O'Brien and Dermot Desmond have told the Moriarty Tribunal they are taking High Court action to stop former Minister for Justice Michael McDowell acting as barrister for the inquiry.
Mr McDowell was brought in by the tribunal for the evidence of a Danish consultant who acting for the state during the second mobile phone licence competition in 1995 and has made a statement saying that then Communications Minister Michael Lowry did not interfere.
But a number of parties objected to Mr McDowell's involvement this morning.
When the sitting resumed after lunch, Bill Shipsey SC for Mr Desmond that he will be taking judicial review proceedings 'with all due haste'.
Jim O'Callaghan SC for Mr O'Brien said he had similar instructions.
Earlier, Mr O'Callaghan said there was appearance of bias in having a former political adversary of Mr Lowry as part of the inquiry.
He also pointed out that as a TD, Mr McDowell had questioned Mr Lowry about the awarding of second mobile licence in 1995.
The hearing then resumed with a statement by tribunal lawyer Jacqueline O'Brien SC on the evidence of the Danish consultant Michael Andersen.
Mr McDowell had been Attorney General when unsuccessful applicants threatened legal action against the State and, as a lawyer, represented Orange in its legal action following the awarding of the third mobile phone licence.
Mr Lowry also questioned whether there was a conflict of interest and said he now had to represent himself because he could not pay a legal team and faced an 'inequality of arms'.
Ms O'Brien SC for the tribunal said there was no conflict of interest as Mr McDowell had not been a minister or attorney general during the mobile phone competition.
Tribunal chairman Mr Justice Michael Moriarty said Mr McDowell had been brought in temporarily because of 'utterly unwarranted slurs and imputations' against the legal team.
Mr McDowell is replacing Michael Coughlan SC for the questioning of Danish consultant for Michael Andersen. Mr Anderson acted for the State in 1995 and has made a statement saying that Mr Lowry did not interfere in the competition.
Mr Andersen's evidence is expected to last two weeks.