The jury at Dublin Circuit Criminal Court were told that Mr Lydon, aged 74, is no longer on trial before them.
The case continues against former councillors Liam Cosgrave and Colm McGrath, sitting councillor Tony Fox, and businessman Jim Kennedy. They all deny charges related to allegations that Mr Kennedy used political lobbyist Frank Dunlop to bribe councillors to vote to rezone potentially valuable land in Carrickmines on dates in Jun 1992 and Oct 1997.
Judge Mary Ellen Ring told the jury she discharged Mr Lydon from the trial after “legal matters” arose.
Earlier, Mr Dunlop admitted obscuring references to the late politician Liam Lawlor and property developer Owen O’Callaghan from his diary.
The diary had been produced to the Mahon Tribunal set up to investigate planning corruption.
The court heard that at the time Mr Dunlop claimed he had obscured the entries accidently by “doodling”. Michael O’Higgins, defending Mr Kennedy, quoted the tribunal as calling this explanation “vague, evasive, and unsatisfactory”.
Mr O’Higgins said that some of these diary entries were uncovered following expert analysis by the FBI and MI5.
Mr Dunlop said he obscured references to Mr O’Callaghan because they were “personal business matter” and not the business of the tribunal. He said he deleted references to Mr Lawlor because he didn’t think they were relevant.
The trial continues.